Document:

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                                                                     EXHIBIT 4.1

================================================================================

                       AMEREN ENERGY GENERATING COMPANY

                                      to

                             THE BANK OF NEW YORK,
                                  as Trustee

                            ----------------------

                                   INDENTURE

                         Dated as of November 1, 2000

                            ----------------------

                 Providing for the Issuance from Time to Time

                     of Senior Notes in One or More Series

================================================================================
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                               TABLE OF CONTENTS

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                                                             ARTICLE I
                                                            DEFINITIONS

Section 1.1       Certain Terms Defined.........................................................................    1

                                                            ARTICLE II
                                       ISSUE, EXECUTION, FORM AND REGISTRATION OF SECURITIES

Section 2.1       Authentication and Delivery of Securities.....................................................   11
Section 2.2       Execution of Securities.......................................................................   12
Section 2.3       Certificate of Authentication.................................................................   13
Section 2.4       Form, Denomination and Date of Securities; Payments of Interest...............................   13
Section 2.5       Global Securities.............................................................................   16
Section 2.6       Registration, Registration of Transfer and Exchange...........................................   17
Section 2.7       Mutilated, Defaced, Destroyed, Lost and Stolen Securities.....................................   22
Section 2.8       Cancellation of Securities; Destruction Thereof...............................................   23
Section 2.9       Temporary Securities..........................................................................   23
Section 2.10      Computation of Interest.......................................................................   24

                                                            ARTICLE III
                                             COVENANTS OF THE ISSUER AND THE TRUSTEE

Section 3.1       Payment of Principal and Interest.............................................................   24
Section 3.2       Offices for Payments, etc.....................................................................   24
Section 3.3       Appointment to Fill a Vacancy in Office of Trustee............................................   24
Section 3.4       Paying Agents.................................................................................   25
Section 3.5       Reports by the Trustee........................................................................   25
Section 3.6       Holders' Lists................................................................................   26
Section 3.7       Reports by the Issuer.........................................................................   27
Section 3.8       Limitation on Liens...........................................................................   28
Section 3.9       Limitations on Subsidiary Indebtedness........................................................   29
Section 3.10      Covenant Not to Merge, Consolidate, Sell or Transfer Assets Except Under Certain Conditions...   29
Section 3.11      Restricted Payments...........................................................................   29
Section 3.12      Debt Incurrence Test..........................................................................   30
Section 3.13      Termination of Financial Covenants............................................................   30

                                                            ARTICLE IV
                                     REMEDIES OF THE TRUSTEE AND HOLDERS ON EVENT OF DEFAULT

Section 4.1       Event of Default Defined; Acceleration of Maturity; Waiver of Default.........................   30
Section 4.2       Collection of Indebtedness by Trustee; Trustee May Prove Debt.................................   33
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Section 4.3       Application of Proceeds.......................................................................   35
Section 4.4       Suits for Enforcement.........................................................................   36
Section 4.5       Restoration of Rights on Abandonment of Proceedings...........................................   36
Section 4.6       Limitations of Suits by Holders...............................................................   36
Section 4.7       Powers and Remedies Cumulative; Delay or Omission Not Waiver of Default.......................   37
Section 4.8       Control by Holders............................................................................   37
Section 4.9       Waiver of Past Defaults.......................................................................   38
Section 4.10      Rights of Holders to Receive Payment..........................................................   38
Section 4.11      Notice of Default.............................................................................   38

                                                             ARTICLE V
                                                      CONCERNING THE TRUSTEE

Section 5.1       Duties and Responsibilities of the Trustee; During Default; Prior to Default..................   39
Section 5.2       Certain Rights of the Trustee.................................................................   39
Section 5.3       Trustee Not Responsible for Recitals, Disposition of Securities or Application of
                  Proceeds Thereof..............................................................................   40
Section 5.4       Trustee and Agents May Hold Securities; Collections, etc......................................   41
Section 5.5       Moneys Held by Trustee........................................................................   41
Section 5.6       Compensation and Indemnification of Trustee and its Prior Claim...............................   41
Section 5.7       Right of Trustee to Rely on Officers' Certificate, etc........................................   41
Section 5.8       Persons Eligible for Appointment as Trustee...................................................   42
Section 5.9       Resignation and Removal; Appointment of Successor Trustee.....................................   42
Section 5.10      Acceptance of Appointment by Successor Trustee................................................   43
Section 5.11      Merger, Conversion, Consolidation or Succession to Business of Trustee........................   43
Section 5.12      Preferential Collection of Claims Against Issuer..............................................   44

                                                            ARTICLE VI
                                                      CONCERNING THE HOLDERS

Section 6.1       Evidence of Action Taken by Holders...........................................................   44
Section 6.2       Proof of Execution of Instruments and of Holding of Securities Record Date....................   44
Section 6.3       Holders to Be Treated as Owners...............................................................   45
Section 6.4       Securities Owned by Issuer Deemed Not Outstanding.............................................   45
Section 6.5       Right of Revocation of Action Taken...........................................................   45

                                                            ARTICLE VII
                                                      SUPPLEMENTAL INDENTURES

Section 7.1       Supplemental Indentures Without Consent of Holders............................................   46
Section 7.2       Supplemental Indentures with Consent of Holders...............................................   47
Section 7.3       Effect of Supplemental Indenture..............................................................   48
Section 7.4       Documents to Be Given to Trustee..............................................................   48
Section 7.5       Notation of Securities in Respect of Supplemental Indentures..................................   48
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                                                           ARTICLE VIII
                                             CONSOLIDATION, MERGER, SALE OR CONVEYANCE

Section 8.1       Successor Corporation Substituted.............................................................   48
Section 8.2       Opinion of Counsel Provided to Trustee; Officers' Certificate.................................   49

                                                            ARTICLE IX
                                     SATISFACTION AND DISCHARGE OF INDENTURE; UNCLAIMED MONEYS

Section 9.1       Satisfaction and Discharge of Indenture.......................................................   49
Section 9.2       Application by Trustee of Funds Deposited for Payment of Securities...........................   50
Section 9.3       Repayment of Moneys Held by Paying Agent......................................................   50
Section 9.4       Return of Moneys Held by Trustee and Paying Agent Unclaimed for Two Years.....................   50
Section 9.5       Defeasance and Discharge of Indenture.........................................................   51
Section 9.6       Defeasance of Certain Obligations.............................................................   52

                                                             ARTICLE X
                                                     MISCELLANEOUS PROVISIONS

Section 10.1      Incorporators, Shareholders, Officers and Directors of Issuer Exempt from Individual
                  Liability.....................................................................................   53
Section 10.2      Provisions of the Indenture for the Sole Benefit of Parties and Holders.......................   53
Section 10.3      Successors and Assigns of Issuer Bound by Indenture...........................................   53
Section 10.4      Notices and Demands on Issuer, Trustee and Holders............................................   54
Section 10.5      Officers' Certificates and Opinions of Counsel; Statements to Be Contained Therein............   54
Section 10.6      Payments Due on Saturdays, Sundays and Holidays...............................................   55
Section 10.7      New York Law to Govern........................................................................   55
Section 10.8      Counterparts..................................................................................   55
Section 10.9      Effect of Headings............................................................................   55
Section 10.10     Subordinated CIPS Note; AmerenCIPS Acknowledgment; Committed Unit Contribution
                  Agreement; Resources Undertaking..............................................................   55
Section 10.11     Trust Indenture Acts Controls.................................................................   56

                                                            ARTICLE XI
                                                     REDEMPTION OF SECURITIES

Section 11.1      Right of Optional Redemption Price............................................................   56
Section 11.2      Notice of Redemption..........................................................................   56
Section 11.3      Payment of Securities Called for Redemption...................................................   57

                                                             EXHIBITS

Exhibit 1         Terms of Subordination
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                                      iii
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         INDENTURE, dated as of November 1, 2000 from AMEREN ENERGY GENERATING
COMPANY, an Illinois corporation (herein called the "Issuer"), to THE BANK OF
                                                     ------
NEW YORK, as trustee (herein called the "Trustee").
                                         -------

                             W I T N E S S E T H:

         WHEREAS, the Issuer has duly authorized the creation of bonds,
debentures, promissory notes or other evidences of indebtedness to be issued in
one or more series (the "Securities") and, to provide, among other things, for
                         ----------
the authentication, delivery and administration thereof, the Issuer has duly
authorized the execution and delivery of this Indenture; and

         WHEREAS, all things necessary to make the Securities, when executed by
the Issuer and authenticated and delivered by the Trustee as in this Indenture
provided, the valid, binding and legal obligations of the Issuer, and to
constitute these presents a valid indenture and agreement according to its
terms, have been done;

         NOW, THEREFORE:

         In consideration of the premises and the purchases of the Securities by
the Holders (as defined herein) thereof, the Issuer and the Trustee mutually
covenant and agree for the equal and proportionate benefit of the respective
Holders from time to time of the Securities as follows:

                                   ARTICLE I

                                  DEFINITIONS
                                  -----------

     Section 1.1  Certain Terms Defined. The following terms (except as
                  ---------------------
otherwise expressly provided) for all purposes of this Indenture shall have the
respective meanings specified in this Section. All accounting terms used herein
and not expressly defined shall have the meanings given to them in accordance
with GAAP (as defined herein). The words "herein," "hereof" and "hereunder" and
                                          ------    ------       ---------
other words of similar import refer to this Indenture as a whole and not to any
particular Article, Section or other subdivision. The terms defined in this
Article include the plural as well as the singular. Unless otherwise specified
herein, any agreement or instrument defined or referred to herein shall include
any amendments, modifications and supplements thereto and waivers thereof made
in accordance with the terms of such agreement or instrument. Unless otherwise
specified herein, each reference to an act, law, rule, regulation or ordinance
shall include such act, law, rule, regulation or ordinance as amended, modified
or supplemented and any successor or replacement for any such act, law, rule,
regulation or ordinance.

     "Agent Members" has the meaning set forth in Section 2.4(c).
     -------------

     "AmerenCIPS" means Central Illinois Public Service Company d/b/a
      ----------
AmerenCIPS, an Illinois corporation.

     "AmerenCIPS Acknowledgment" means that certain letter agreement between
      -------------------------
the Issuer and AmerenCIPS, dated November 1, 2000 relating to the Subordinated
CIPS Note.
<PAGE>

          "AmerenUE" means Union Electric Company d/b/a AmerenUE, a Missouri
           --------
corporation.

          "Applicable Premium" with respect to the Securities of a series, has
           ------------------
the meaning set forth in the Series Supplemental Indenture relating thereto.

          "Asset Sale" shall mean any sale, lease (except for the lease of the
           ----------
Joppa 7B generating stations so long as the Issuer or a Subsidiary remains the
lessor), sale-leaseback, transfer, conveyance or other disposition of any assets
including by way of the issue by the Issuer or any of its Subsidiaries of equity
interests in such Subsidiaries, except (a) in the ordinary course of business to
the extent that such property is (i) worn out or is no longer useful or
necessary in connection with the operation of the Issuer's business or sale
inventory or (ii) being transferred to a wholly-owned Subsidiary of the Issuer
or (b) if, prior to such conveyance or disposition, each Rating Agency then
rating any of the Securities provides a Rating Reaffirmation of the then
existing rating of such Securities after giving effect to such Asset Sale.

          "Asset Transfer Agreement" means that certain Asset Transfer
           ------------------------
Agreement, dated as of May 1, 2000, between AmerenCIPS and the Issuer.

          "Available Cash" means, for a given period, all funds of the Issuer
           --------------
remaining after payment of all operating and maintenance expenditures, Senior
Debt Service, capital expenditures, taxes and reasonable reserves for working
capital and other corporate purposes determined by the Issuer in its discretion,
in each case, for such period.

          "Board of Directors" means either the Board of Directors of the Issuer
           ------------------
or any committee of such Board duly authorized to act on behalf of such Board.

          "Business Day" means a day which is neither a legal holiday nor a day
           ------------
on which banking institutions (including, without limitation, the Federal
Reserve System) are authorized or required by law or regulation to close in The
City of New York or The City of St. Louis, Missouri.

          "Cash Flow Available for Senior Debt" for any period means, without
           -----------------------------------
duplication, (i) EBITDA of the Issuer and its consolidated Subsidiaries for such
period, minus (ii) EBITDA for such period of the consolidated Subsidiaries, if
        -----
any, of the Issuer that are financed with Indebtedness that does not constitute
Indebtedness of the Issuer, plus (iii) distributions received by the Issuer from
                            ----
Subsidiaries described in the foregoing clause (ii) during such period, minus
                                                                        -----
(iv) distributions described in the foregoing clause (iii) that are attributable
to extraordinary gains or other non-recurring items included in EBITDA, minus
                                                                        -----
(v) any income reported by the Issuer for such period for Persons that are not
consolidated Subsidiaries of the Issuer that are financed with Indebtedness that
does not constitute Indebtedness of the Issuer, plus (vi) distributions received
                                                ----
by the Issuer from Persons described in the foregoing clause (v) during such
period, minus (vii) distributions described in the foregoing clause (vi) that
        -----
are attributable to extraordinary gains or other non-recurring items included in
EBITDA.

          "Clearstream" has the meaning set forth in Section 2.4(b).
           -----------

          "Commission" means the U.S. Securities and Exchange Commission, as
           ----------
from time to time constituted, created under the Exchange Act, or, if at any
time after the execution of this

                                       2
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Indenture such Commission is not existing and performing the duties now assigned
to it under the Trust Indenture Act, then the body (if any) performing such
duties at such time.

         "Committed Unit Contribution Agreement" means the Committed Unit
          -------------------------------------
Contribution Agreement, dated as of November 1, 2000, between the Issuer and
Ameren Energy Resources Company (on behalf of itself and Ameren Energy
Development Company) in respect of the Committed Units and any additional
combustion turbine units that, at the option of the Issuer, become subject to
the Committed Unit Contribution Agreement.

         "Committed Units" means the new combustion turbine generation
          ---------------
facilities at the Issuer's Grand Tower station and Kinmundy station in Illinois.

         "Consolidated Tangible Assets" means (at any date of determination) the
          ----------------------------
total assets of the Issuer and its Subsidiaries determined in accordance with
GAAP, excluding, however, from the determination of total assets (a) goodwill,
organizational expenses, research and product development expenses, trademarks,
tradenames, copyrights, patents, patent applications, licenses and rights in any
thereof, and other similar intangibles, (b) all deferred charges or unamortized
debt discount and expenses, (c) all reserves carried and not deducted from
assets, (d) securities which are not readily marketable, (e) cash held in
sinking or other analogous funds established for the purpose of redemption,
retirement or prepayment of capital stock or other equity interests or debt, (f)
any write-up in the book value of any assets resulting from a revaluation
thereof subsequent to June 30, 2000, and (g) any items not included in clauses
(a) through (f) above which are treated as intangibles in conformity with GAAP.
Consolidated Tangible Assets shall in any case include the aggregate net book
value of all asset sales or dispositions made by the Issuer and any of its
Subsidiaries since November 1, 2000 to the extent that the proceeds thereof or
other consideration received therefor are not invested or reinvested in a
Permitted Business, or are not retained by the Issuer or its Subsidiaries.

         "Corporate Trust Office" means the principal office of the Trustee at
          ----------------------
which the corporate trust business of the Trustee shall, at any particular time,
be principally administered, which office is, at the date as of which this
Indenture is dated, located at 101 Barclay Street, New York, New York 10286.

         "EBITDA" means, with respect to any Person for any period, the (i)
          ------
income (or loss) before interest and taxes of such person, plus (ii) to the
extent deducted in determining such income (or loss), depreciation, amortization
and other similar non-cash charges and reserves, minus (iii) to the extent
recognized in determining such income (or loss), extraordinary gains (or
losses), restructuring charges or other non-recurring items, plus (iv) to the
extent deducted in determining such income (or loss), lease obligations of the
type referred to in clause (v) of the definition of Indebtedness.

         "Euroclear" has the meaning set forth in Section 2.4(b).
          ---------

         "Event of Default" means any event or condition specified as such in
          ----------------
Section 4.1 hereof that shall have continued for the period of time, if any,
therein designated.

         "Exchange Act" means the Securities Exchange Act of 1934, as amended.
          ------------

                                       3
<PAGE>

         "Exchange Notes" means the Securities issued hereunder and in
          --------------
accordance with the terms of the Registration Rights Agreement in exchange for
the Series A Notes and Series B Notes.

         "GAAP" means generally accepted accounting principles in the U.S.
          ----
applied on a basis consistent with the principles, methods, procedures and
practices employed in the preparation of the Issuer's audited financial
statements, including, without limitation, those set forth in the opinions and
pronouncements of the Accounting Principles Board of the American Institute of
Certified Public Accountants and statements and pronouncements of the Financial
Accounting Standards Board or in such other statements by such other entity as
approved by a significant segment of the accounting profession.

         "Genco-Marketing Co. PPA" means the Electric Power Supply Agreement
          -----------------------
dated May 1, 2000 and amended August 14, 2000 between the Issuer and Marketing
Co.

         "Global Security" has the meaning set forth in Section 2.4(c).
          ---------------

         "Holder," "Holder of Securities" and other similar terms mean the
          ------    --------------------
registered holder of any Security.

         "IAI Global Security" has the meaning set forth in Section 2.4(b).
          -------------------

         "Indebtedness" of any Person shall mean (i) all indebtedness of such
          ------------
Person for borrowed money, (ii) all obligations of such Person evidenced by
bonds, debentures, notes or other similar instruments, (iii) all obligations of
such Person to pay the deferred purchase price of property or services, (iv) all
indebtedness created or arising under any conditional sale or other title
retention agreement with respect to property acquired by such Person (even
though the rights and remedies of the seller or lender under such agreement in
the event of default are limited to repossession or sale of such property), (v)
all capital lease obligations of such Person (excluding leases of property in
the ordinary course of business), (vi) all obligations, contingent or otherwise,
of such Person under acceptance, letter of credit or similar facilities other
than commercial leases, (vii) all unconditional obligations of such Person to
purchase, redeem, retire, defease or otherwise acquire for value any capital
stock or other equity interests of such Person or any warrants, rights, or
options to acquire such capital stock or other equity interests, (viii) all
Indebtedness of any other Person of the type referred to in clauses (i) through
(vii) guaranteed by such Person or for which such Person shall otherwise
(including pursuant to any keepwell, makewell or similar arrangement) become
directly or indirectly liable, and (ix) all Indebtedness of the type referred to
in clauses (i) through (vii) above secured by (or for which the holder of such
Indebtedness has an existing right, contingent or otherwise, to be secured by)
any lien or security interest on property.

         "Indenture" means this instrument as originally executed and delivered
          ---------
or, if amended or supplemented as herein provided, as so amended or
supplemented.

         "Initial Generating Assets" means the Newton, Coffeen, Meredosia,
          -------------------------
Hutsonville, Grand Tower, Gibson City (Units 1 and 2), Kinmundy (Units 1 and 2),
and Pinckneyville (Units 1, 2, 3 and 4) generating stations and the Issuer's or
a Subsidiary's interest as lessor in the lease of the Joppa 7B generating
stations placed in service during the third calendar quarter of 2000.

                                       4
<PAGE>

         "Initial Purchasers" means Lehman Brothers Inc., Chase Securities Inc.,
          ------------------
Banc of America Securities LLC, Banc One Capital Markets, Inc. and BNY Capital
Markets, Inc.

         "Intangible Assets" means, as of the date of determination thereof, all
          -----------------
assets of the Issuer properly classified as intangible assets determined on a
consolidated basis in accordance with GAAP.

         "Interest Payment Date" means, with respect to any Security, the Stated
          ---------------------
Maturity of an installment of interest on such Security.

         "Investment Banker" means an independent investment banking institution
          -----------------
of national standing selected by the Issuer.

         "Issuer" means Ameren Energy Generating Company, and, subject to
          ------
Article 3 and Article 8 hereof, its successors and assigns.

         "Legend" has the meaning set forth in Section 2.6(d).
          ------

         "Marketing Co." means Ameren Energy Marketing Company, an Illinois
          ------------
corporation.

         "Marketing Co.-CIPS PPA" means the Electric Power Supply Agreement
          ----------------------
dated May 1, 2000 between AmerenCIPS and Marketing Co.

         "Non-utility Money Pool Borrowings" means borrowings by the Issuer
          ---------------------------------
under Ameren Corporation's non-utility money pool agreement.

         "Officers' Certificate" means a certificate signed on behalf of the
          ---------------------
Issuer by the President or any Vice President and by the Controller or the
Secretary or any Assistant Secretary or the Treasurer or any Assistant Treasurer
of the Issuer and delivered to the Trustee. Each such certificate shall include
the statements provided for in Section 10.5 hereof, if and to the extent
required thereby.

         "Opinion of Counsel" means an opinion in writing signed by legal
          ------------------
counsel satisfactory to the Trustee, who may be an employee of or counsel to the
Issuer. Each such opinion shall include the statements provided for in Section
10.5 hereof, if and to the extent required thereby.

         "Original Issue Date" of any Security (or portion thereof) means the
          -------------------
earlier of (a) the date of such Security or (b) the date of any Security (or
portion thereof) in exchange for which such Security was issued (directly or
indirectly) on registration of transfer, exchange or substitution.

         "Outstanding", when used with reference to Securities, shall, subject
          -----------
to the provisions of Section 6.4 hereof, mean, as of any particular time, all
Securities authenticated and delivered by the Trustee under this Indenture,
except:

               1. Securities theretofore canceled by the Trustee or delivered
         to the Trustee for cancellation, or which shall have been paid pursuant
         to Section 2.7 hereof (other than any such Securities in respect of
         which there shall have been presented to the Trustee

                                       5
<PAGE>

         proof satisfactory to it that such Securities are held by a bona fide
         purchaser in whose hands the Securities are valid obligations of the
         Issuer); and

               2. Securities, or portions thereof, for the payment or redemption
         of which U.S. Government Obligations in the necessary amount shall have
         been deposited in trust with the Trustee or with any paying agent
         (other than the Issuer) or shall have been set aside, segregated and
         held in trust by the Issuer (if the Issuer shall act as its own paying
         agent), provided that if such Securities are to be redeemed prior to
                 --------
         the maturity thereof, notice of such redemption shall have been herein
         provided, or provision satisfactory to the Trustee shall have been
         given as herein provided, or provision satisfactory to the Trustee
         shall have been made for giving such notice.

         "Parent", with respect to any Person, means any other Person who
          ------
directly or indirectly owns more than 50% of the voting equity interests of such
Person.

         "Permitted Business" means a business that is the same or similar to
          ------------------
the business of the Issuer as of the date that Securities are first
authenticated hereunder, or any business reasonably related thereto, including
advances made by the Issuer pursuant to a valid Committed Unit Contribution
Agreement.

         "Permitted Indebtedness" means (i) the Subordinated Intercompany Notes,
          ----------------------
(ii) Non-utility Money Pool Borrowings, (iii) Subordinated Parent Borrowings,
(iv) tax-exempt pollution control loan obligations not to exceed $104 million in
aggregate principal amount, (v) the Series A Notes and Series B Notes and (vi)
the Exchange Notes.

         "Person" means an individual, a corporation, a partnership, a limited
          ------
liability company, an association, a trust or any other entity or organization,
including a government or political subdivision or an agency or instrumentality
thereof.

         "Pro Forma Basis" means, for the purpose of Section 3.12 and the making
          ---------------
of a Restricted Payment described in clause (iii) of the definition of
Restricted Payments, that

         (i)   if the Issuer or any Subsidiary has incurred any Indebtedness
since the beginning of such period that remains outstanding on such date of
determination or if the transaction giving rise to the need to calculate the
Senior Debt Service Coverage Ratio or the Senior Debt to Capital Ratio is an
incurrence of Indebtedness, EBITDA and Senior Debt Service for such period shall
be calculated after giving effect on a pro forma basis to such Indebtedness as
if such Indebtedness had been incurred on the first day of such period and the
discharge of any other Indebtedness repaid, repurchased, defeased or otherwise
discharged with the proceeds of such new Indebtedness as if such discharge had
occurred on the first day of such period,

         (ii)  if the Issuer or any Subsidiary has repaid, repurchased,
defeased or otherwise discharged any Indebtedness since the beginning of such
period or if any Indebtedness is to be repaid, repurchased, defeased or
otherwise discharged (in each case other than Indebtedness incurred under any
revolving credit facility unless such Indebtedness has been permanently repaid
and has not been replaced) on the date of the transaction giving rise to the
need to calculate the Senior Debt Service Coverage Ratio or the Senior Debt to
Capital Ratio, EBITDA and Senior Debt Service for such period shall be
calculated on a pro forma basis as if such

                                       6
<PAGE>

discharge had occurred on the first day of such period and as if the Issuer or
such Subsidiary has not earned the interest income actually earned during such
period in respect of cash or temporary cash investments used to repay,
repurchase, defease or otherwise discharge such Indebtedness,

         (iii) if since the beginning of such period the Issuer or any
Subsidiary shall have made any Asset Sale, EBITDA for such period shall be
reduced by an amount equal to EBITDA (if positive) directly attributable to the
assets that are the subject of such Asset Sale for such period or increased by
an amount equal to EBITDA (if negative) directly attributable thereto for such
period and Senior Debt Service for such period shall be reduced by an amount
equal to the Senior Debt Service directly attributable to any Indebtedness of
the Issuer or any Subsidiary repaid, repurchased, defeased or otherwise
discharged with respect to the Issuer and its continuing Subsidiaries in
connection with such Asset Sale for such period (or, if the capital stock of any
Subsidiary is sold, the Senior Debt Service for such period directly
attributable to the Indebtedness of such Subsidiary to the extent the Issuer and
its continuing Subsidiaries are no longer liable for such Indebtedness after
such sale),

         (iv)  if since the beginning of such period the Issuer or any
Subsidiary (by merger or otherwise) shall have made an investment in any
Subsidiary (or any Person that becomes a Subsidiary) or an acquisition of
assets, including any acquisition of assets occurring in connection with a
transaction causing a calculation of the Senior Debt Service Coverage Ratio or
the Senior Debt to Capital Ratio to be made hereunder, which constitutes all or
substantially all of an operating unit of a business, EBITDA and Senior Debt
Service for such period shall be calculated after giving pro forma effect
thereto (including the incurrence of any Indebtedness) as if such investment or
acquisition occurred on the first day of such period, and

         (v)   if since the beginning of such period any Person (that
subsequently became a Subsidiary or was merged with or into the Issuer or any
Subsidiary since the beginning of such period) shall have made any Asset Sale or
any investment or acquisition of assets that would have required an adjustment
pursuant to clause (iii) or (iv) above if made by the Issuer or a Subsidiary
during such period, EBITDA and Senior Debt Service for such period shall be
calculated after giving pro forma effect thereto as if such Asset Sale,
investment or acquisition of assets occurred on the first day of such period

         For purposes of this definition, whenever pro forma effect is to be
given to an acquisition of assets or other investment, the amount of income or
earnings relating thereto and the amount of Senior Debt Service associated with
any Indebtedness incurred in connection therewith, the pro forma calculations
shall be determined in good faith by a responsible financial or accounting
officer of the Issuer and shall comply with the requirements of Rule 11-02 of
Regulation S-X promulgated by the Commission

         If any Indebtedness bears a floating rate of interest and is being
given pro forma effect, the interest expense on such Indebtedness shall be
calculated as if the rate in effect on the date of determination had been and
will be the applicable rate for the entire period (taking into account any
interest rate agreement applicable to such Indebtedness if such interest rate
agreement has a remaining term as at the date of determination of 12 months or
more).

                                       7
<PAGE>

         "Purchase Agreement" means the Note Purchase Agreement dated October
          ------------------
25, 2000 between the Issuer and Lehman Brothers Inc., on behalf of the Initial
Purchasers.

         "Rating Agencies" means Moody's Investors Service, Inc. and Standard &
          ---------------
Poor's Ratings Services.

         "Ratings Reaffirmation" means a reaffirmation by a rating agency of its
          ---------------------
original or then current credit ratings (as applicable, as provided in this
Indenture) of all of the Securities Outstanding which are then subject to a
credit rating, giving effect to the transactions giving rise to such request for
reaffirmation.

         "Registration Rights Agreement" means the Registration Rights
          -----------------------------
Agreement, dated November 1, 2000, between the Issuer and the Initial
Purchasers.

         "Regulation S" has the meaning set forth in Section 2.4(b).
          ------------

         "Resources Undertaking" shall mean the Resources Letter of Undertaking
          ---------------------
from Ameren Energy Resources Company to the Issuer relating to the Subordinated
CIPS Note, dated as of November 1, 2000.

         "Responsible Officer", when used with respect to the Trustee, means any
          -------------------
officer of the Trustee assigned by the Trustee to administer its corporate trust
matters.

         "Restricted Payments" means, collectively, (i) distributions including
          -------------------
payments of dividends or redemptions or repurchases of ownership interests in
the Issuer; (ii) payments of principal, interest or premium, if any, on and any
repurchases of any Subordinated Parent Borrowings or other subordinated
Indebtedness the Issuer may issue (including to an affiliate); and (iii)
investments made by the Issuer or any Subsidiary in any partnership, joint
venture or other entity which is not a Subsidiary. Restricted Payments shall not
include (A) payments in respect of the Subordinated CIPS Note, (B) investments
in the Ameren Corporation non-utility money pool, (C) repayments of Non-utility
Money Pool Borrowings and (D) advances made by the Issuer pursuant to the terms
of a valid Committed Unit Contribution Agreement. Restricted Payments also shall
not include redemptions or repurchases of the Issuer's ownership interests or
other subordinated Indebtedness with the proceeds from the substantially
concurrent issuance by the Issuer of other ownership interests or other
subordinated Indebtedness.

         "Restricted Regulation S Global Security" has the meaning set forth in
          ---------------------------------------
Section 2.4(b).

         "Rule 144A" has the meaning set forth in Section 2.4(b).
          ---------

         "Rule 144A Global Security" has the meaning set forth in Section
          -------------------------
2.4(b).

         "Securities Act" means the Securities Act of 1933, as amended.
          --------------

         "Security" or "Securities" has the meaning set forth in the recitals
          --------      ----------
above.

         "Securities Register" and "Security Registrar" have the respective
          -------------------       ------------------
meanings specified in Section 2.6 hereof.

                                       8
<PAGE>

         "Senior Debt Service" means, with respect to any Person for any period,
          -------------------
the sum, without duplication, of (i) the aggregate amount of interest expense
with respect to Indebtedness of such Person for such period including (A) the
net costs under interest rate hedge agreements, (B) all capitalized interest,
(C) the interest portion of any deferred payment obligation and (D) payments in
the nature of interest under lease obligations of such Person scheduled to be
paid by such Person during such period (in each case, exclusive of Indebtedness
which is by its terms subordinated in right of payment to any other Indebtedness
of the Issuer, including, but not limited to, the Subordinated Intercompany
Notes and Subordinated Parent Borrowings), and (ii) the aggregate amount of all
mandatory scheduled payments (whether designated as payments or prepayments) and
sinking fund payments with respect to principal of any Indebtedness of such
Person, including payments in the nature of principal under lease obligations,
in each case scheduled to be paid by such Person during such period (in each
case, exclusive of Indebtedness which is by its terms subordinated in right of
payment to any other Indebtedness of the Issuer, including, but not limited to,
the Subordinated Intercompany Notes and Subordinated Parent Borrowings).

         "Senior Debt Service Coverage Ratio" for any period means, the ratio of
          ----------------------------------
(i) Cash Flow Available for Senior Debt for such period to (ii) Senior Debt
Service for such period.

         "Senior Debt to Capital Ratio" means, with respect to any Person, the
          ----------------------------
ratio as of the most recent fiscal quarter for which financial statements have
been delivered to the Trustee pursuant to Section 3.7 hereof of (i) the
aggregate principal amount of Senior Indebtedness of such Person then
outstanding to (ii) Total Capitalization.

         "Senior Indebtedness" means all Indebtedness of the Issuer, exclusive
          -------------------
of Indebtedness which is by its terms subordinated in right of payment to any of
the Issuer's other Indebtedness, including, but not limited to, the Subordinated
Intercompany Notes and Subordinated Parent Borrowings.

         "Series A Notes and Series B Notes" means the Securities issued under
          ---------------------------------
the First Supplemental Indenture dated as of November 1, 2000 and consisting of
$225,000,000 7.75% Senior Notes, Series A due 2005 and $200,000,000 8.35% Senior
Notes, Series B due 2010.

         "Series Supplemental Indenture" means an indenture supplemental to this
          -----------------------------
Indenture entered into by the Issuer and the Trustee for the purpose of
establishing, in accordance with this Indenture, the title, form and terms of
the Securities of any series; "Series Supplemental Indentures" means each and
every Series Supplemental Indenture.

         "Stated Maturity" means, with respect to any debt security or any
          ---------------
installment of interest thereon, the date specified in such debt security as the
fixed date on which any principal of such debt security or any such installment
of interest is due and payable.

         "Subordinated Ameren Note" means the subordinated note issued by the
          ------------------------
Issuer to Ameren Corporation on June 30, 2000 in the amount of $50 million, and,
provided that there is no increase in the principal amount thereof, any
refinancing or extension thereof.

         "Subordinated CIPS Note" means the subordinated notes issued by the
          ----------------------
Issuer to AmerenCIPS in the aggregate amount of $552 million pursuant to the
Asset Transfer Agreement

                                       9
<PAGE>

and, provided that there is no increase in the principal amount thereof, any
refinancing or extension thereof.

         "Subordinated Intercompany Notes" means collectively (i) the
          -------------------------------
Subordinated Ameren Note and (ii) the Subordinated CIPS Note.

         "Subordinated Parent Borrowings" means the Subordinated Ameren Note and
          ------------------------------
any other borrowings by the Issuer from a Parent, provided that such borrowings
are subordinated on terms substantially similar to the terms of subordination
attached hereto as Exhibit 1.

         "Subsidiary" means any corporation or other entity of which sufficient
          ----------
voting stock or other ownership or economic interests having ordinary voting
power to elect a majority of the board of directors (or equivalent body) are at
the time directly or indirectly held by the Issuer.

         "Total Capitalization" means, with respect to any Person, the sum,
          --------------------
without duplication, of (i) total common stock equity or analogous ownership
interests of such Person, (ii) preferred stock and preferred securities of such
Person, (iii) additional paid in capital or analogous interests of such Person,
(iv) retained earnings of such Person and (v) the aggregate principal amount of
Indebtedness (including all intercompany notes) of such Person then outstanding.

         "Trust Indenture Act" means the Trust Indenture Act of 1939, as
          -------------------
amended.

         "Trustee" means the entity identified as "Trustee" in the first
          -------
paragraph hereof until the appointment of a successor trustee pursuant to
Article 5, after which "Trustee" shall mean such successor trustee.

         "Unrestricted Regulation S Global Security" has the meaning set forth
          -----------------------------------------
in Section 2.4(b).

         "U.S. Depositary" has the meaning set forth in Section 2.4(b).
          ---------------

         "U.S. Government Obligations" means securities that are (i) direct and
          ---------------------------
unconditional obligations of the United States of America for the payment of
which its full faith and credit is pledged or (ii) obligations of a Person
controlled or supervised by, and acting as an agency or instrumentality of, the
United States of America, the payment of which is unconditionally guaranteed as
a full faith and credit obligation by the United States of America, which, in
either case are not callable or redeemable at the option of the issuer thereof,
and shall also include a depository receipt issued by a bank or trust company
subject to federal or state supervision or examination with a combined capital
and surplus of at least $100,000,000, as custodian with respect to any such U.S.
Government Obligations or a specific payment of interest on or principal of any
such U.S. Government Obligation held by such custodian for the account of the
holder of a depository receipt, provided that (except as required by law) such
                                --------
custodian is not authorized to make any deduction from the amount payable to the
holder of such depository receipt from any amount received by the custodian in
respect of the U.S. Government Obligation or the specific payment of interest on
or principal of the U.S. Government Obligation evidenced by such depository
receipt.

                                       10
<PAGE>

                                  ARTICLE II

             ISSUE, EXECUTION, FORM AND REGISTRATION OF SECURITIES
             -----------------------------------------------------

     Section 2.1.   Authentication and Delivery of Securities. The Securities
                    -----------------------------------------
of each series shall be substantially in the form established in the Series
Supplemental Indenture relating to the Securities of such series. Upon the
execution and delivery of this Indenture and a Series Supplemental Indenture, a
series of Securities may be executed by the Issuer and delivered to the Trustee
for authentication, and the Trustee shall thereupon authenticate and deliver
said Securities to or upon the written order of the Issuer, signed by both (i)
its President or any Vice President and (ii) by its Controller, or its Secretary
or any Assistant Secretary, or its Treasurer or any Assistant Treasurer without
any further action by the Issuer. The Securities of each series shall be direct,
unconditional obligations of the Issuer and shall rank pari passu without
preference among themselves or among the Securities of each other series by
reason of difference in time of issuance or otherwise and equally in priority of
payment with all other present and future unsubordinated, unsecured Indebtedness
of the Issuer.

     The aggregate principal amount of Securities that may be authenticated and
delivered under this Indenture is unlimited.

               (b)  The Securities may be issued in one or more series. There
shall be established in one or more Series Supplemental Indentures, prior to the
issuance of Securities of any series:

                    (i)   the title of the Securities of such series (which
          shall distinguish the Securities of such series from all other
          Securities) and the form or forms of Securities of such series;

                    (ii)  any limit upon the aggregate principal amount of the
          Securities of such series that may be authenticated and delivered
          under this Indenture (except for Securities authenticated and
          delivered upon registration of transfer of, or in exchange for, or in
          lieu of, other Securities of such series pursuant to Section 2.5, 2.7
          or 2.9);

                    (iii) the date or dates on which the principal of the
          Securities of such series is payable, the amounts of principal payable
          on such date or dates and the record date for the determination of
          Holders to whom principal is payable; and the date or dates on or as
          of which the Securities of such series shall be dated;

                    (iv)  the rate or rates at which the Securities of such
          series shall bear interest, or the method by which such rate or rates
          shall be determined, the date or dates from which such interest shall
          accrue, the interest payment dates on which such interest shall be
          payable and the record date for the determination of Holders to whom
          interest is payable, and the basis of computation of interest;

                    (v)   if other than as provided in this Indenture, the place
          or places where (i) the principal of, premium, if any, and interest on
          Securities of such series shall be payable, (ii) Securities of such
          series may be surrendered for registration of transfer or

                                       11
<PAGE>

          exchange and (iii) notices and demands to or upon the Issuer in
          respect of the Securities of such series and this Indenture may be
          served;

                    (vi)   if other than as provided in this Indenture, the
          price or prices at which, the period or periods within which and the
          terms and conditions upon which Securities of such series may be
          redeemed, in whole or in part, at the option of the Issuer;

                    (vii)  the obligation, if any, of the Issuer to redeem,
          purchase or prepay Securities of such series pursuant to any sinking
          fund or analogous provisions or at the option of a Holder thereof or
          upon the occurrence of a specified event and the price or prices at
          which, the period or periods within which and the terms and conditions
          upon which Securities of such series shall be redeemed, purchased or
          prepaid, in whole or in part, pursuant to such obligations;

                    (viii) if other than denominations of $100,000 and integral
          multiples of $1,000 in excess thereof, the denominations in which
          Securities of such series shall be issuable;

                    (ix)   any other terms of such series, including any
          additional covenants benefiting only the holders of such Securities
          (which terms shall not be inconsistent with the provisions of this
          Indenture); and

                    (x)    any trustees, authenticating or paying agents,
          warrant agents, transfer agents or registrars with respect to the
          Securities of such series.

          (c)       All Securities of any one series shall be substantially
identical except as to denomination and except as may otherwise be provided
herein or in the Series Supplemental Indenture setting forth the terms of the
Securities of such series. A Series Supplemental Indenture may provide that any
covenant for the benefit of the Holders of Securities included in this Indenture
(other than those in Sections 3.1 through and including 3.6 hereof) shall not
apply with respect to the Securities created under such Series Supplemental
Indenture.

     Section 2.2    Execution of Securities. The Securities shall be signed on
                    -----------------------
behalf of the Issuer by its President, any Vice President or its Treasurer and
attested to by its Secretary or an Assistant Secretary. Such signatures may be
the manual or facsimile signatures of the present or any future such officers.
The seal of the Issuer may be in the form of a facsimile thereof and may be
impressed, affixed, imprinted or otherwise reproduced on the Securities.
Typographical and other minor errors or defects in any such reproduction of the
seal or any such signature shall not affect the validity or enforceability of
any Security that has been duly authenticated and delivered by the Trustee.

     In case any officer of the Issuer who shall have signed any of the
Securities shall cease to be such officer before the Security so signed shall be
authenticated and delivered by the Trustee or disposed of by the Issuer, such
Security nevertheless may be authenticated and delivered or disposed of as
though the Person who signed such Security had not ceased to be such officer of
the Issuer; and any Security may be signed on behalf of the Issuer by such
Persons as, at the actual date of the execution of such Security, shall be the
proper officers of the Issuer, although at the date of the execution and
delivery of this Indenture any such Person was not such officer.

                                       12
<PAGE>

     Section 2.3    Certificate of Authentication. Only such Securities as shall
                    -----------------------------
bear thereon a certificate of authentication substantially in the form recited
in the form of Security attached as Exhibit A to the related Series Supplemental
Indenture, executed by the Trustee by manual signature of one of its authorized
signatories, shall be entitled to the benefits of this Indenture or be valid or
obligatory for any purpose. Such certificate by the Trustee upon any Security
executed by the Issuer shall be conclusive evidence that the Security so
authenticated has been duly authenticated and delivered hereunder and that the
Holder is entitled to the benefits of this Indenture.

     Section 2.4    Form, Denomination and Date of Securities; Payments of
                    ------------------------------------------------------
Interest. (a) The Securities and the Trustee's certificate of authentication
--------
shall be substantially in the form set forth in the form of Security attached as
Exhibit A to the related Series Supplemental Indenture. The Securities shall be
numbered, lettered, or otherwise distinguished in such manner or in accordance
with such plans as the officers of the Issuer executing the same may determine
with the approval of the Trustee.

     Any of the Securities may be issued with appropriate insertions, omissions,
substitutions and variations, and may have imprinted or otherwise reproduced
thereon such legend or legends, not inconsistent with the provisions of this
Indenture, as may be required to comply with any law or with any rules or
regulations pursuant thereto, or with the rules of any securities market in
which the Securities are admitted to trading, or to conform to general usage.

               (b)  Securities of a series offered and sold in reliance on
Regulation S under the Securities Act ("Regulation S") shall be issued in the
                                        ------------
form of a permanent Global Security (as defined herein) in definitive, fully
registered form without interest coupons substantially in the form of Security
attached as Exhibit A to the related Series Supplemental Indenture with such
legends as may be applicable thereto in accordance with such form, which shall
be deposited on behalf of such purchasers of such Securities represented thereby
with the Trustee at the Corporate Trust Office, as custodian for The Depository
Trust Company (hereinafter, the "U.S. Depositary") and registered in the name of
                                 ---------------
a nominee of the U.S. Depositary, duly executed by the Issuer and authenticated
by the Trustee as hereinafter provided, for credit to their respective accounts
(or to such other accounts as they may direct) at Morgan Guaranty Trust Company
of New York, Brussels office, as operator of the Euroclear System ("Euroclear")
                                                                    ---------
or Clearstream, Luxembourg Banking, S.A. ("Clearstream"). Until the termination
                                           -----------
of the restricted period (as defined in Regulation S) with respect to the offer
and sale of Securities, interests in such Global Security may only be held by
the Agent Members (as defined herein) for Euroclear and Clearstream. Until such
time as the restricted period shall have terminated, such Global Security shall
be referred to herein as the "Restricted Regulation S Global Security." After
                              ---------------------------------------
such time as the restricted period shall have terminated, such Global Security
shall be referred to herein as the "Unrestricted Regulation S Global Security."
                                    -----------------------------------------
The aggregate principal amount of the Restricted Regulation S Global Security
and the Unrestricted Regulation S Global Security may from time to time be
increased or decreased by adjustments made on the records of the Trustee, as
custodian for the U.S. Depositary, as herein provided. The Issuer shall notify
the Trustee of the termination of the restricted period by furnishing to the
Trustee a certificate substantially in the form of Exhibit B to the related
Series Supplemental Indenture.

                                       13
<PAGE>

     Securities of a series offered and sold in reliance on Rule 144A under the
Securities Act ("Rule 144A") shall be issued in the form of a permanent Global
                 ---------
Security (the "Rule 144A Global Security") in definitive fully registered form
               -------------------------
without interest coupons substantially in the form of Security attached as
Exhibit A to the related Series Supplemental Indenture with such legends as may
be applicable thereto in accordance with the form of such Security deposited
with the Trustee, at the Corporate Trust Office, as custodian for the U.S.
Depositary, duly executed by the Issuer and authenticated by the Trustee as
herein provided. The aggregate principal amount of the Rule 144A Global Security
may from time to time be increased or decreased by adjustments made on the
records of the Trustee, as custodian for the U.S. Depositary, and the U.S.
Depositary or its nominee, as the case may be, as herein provided.

     Securities of a series offered and sold to institutions that are
"accredited investors" within the meaning of Rule 501(a)(1), (2), (3) or (7) of
the Securities Act shall be issued in the form of a permanent Global Security
(the "IAI Global Security") in definitive fully registered form without interest
      -------------------
coupons substantially in the form of Security attached as Exhibit A to the
related Series Supplemental Indenture with such legends as may be applicable
thereto in accordance with the form of such Security deposited with the Trustee,
at the Corporate Trust Office, as custodian for the U.S. Depositary, duly
executed by the Issuer and authenticated by the Trustee as herein provided. The
aggregate principal amount of the IAI Global Security may from time to time be
increased or decreased by adjustments made on the records of the Trustee, as
custodian for the U.S. Depositary, and the U.S. Depositary or its nominee, as
the case may be, as herein provided.

               (c)  (i)   This Section 2.4(c)(i) shall apply only to Securities
of a series in global form ("Global Securities") deposited with the U.S.
                             -----------------
Depositary.

          The Issuer shall execute and the Trustee shall, in accordance with
this Section 2.4(c)(i), authenticate and deliver initially Global Securities
that (a) shall be registered in the name of the U.S. Depositary for such Global
Securities or the nominee of such U.S. Depositary, (b) shall be deposited on
behalf of Agent Members (as defined herein) with the Trustee as custodian for
the U.S. Depositary and (c) shall bear legends substantially to the following
effect:

          "UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE
OF [INSERT NAME AND ADDRESS OF U.S. DEPOSITARY] TO THE ISSUER OR ITS AGENT FOR
REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IN
EXCHANGE FOR THIS CERTIFICATE OR ANY PORTION HEREOF IS REGISTERED IN THE NAME OF
[INSERT NAME OF U.S. NOMINEE OF DEPOSITARY], OR TO SUCH OTHER ENTITY AS IS
REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF [INSERT NAME OF U.S. DEPOSITARY],
OR SUCH OTHER NAME AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF [INSERT
NAME OF U.S. DEPOSITARY] (AND ANY PAYMENT HEREON IS MADE TO [INSERT NAME OF
NOMINEE OF U.S. DEPOSITARY]), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE
OR OTHERWISE BY OR TO ANY PERSON OTHER THAN [INSERT NAME OF U.S. DEPOSITARY OR A
NOMINEE THEREOF] IS WRONGFUL INASMUCH AS THE REGISTERED OWNER HEREOF, [INSERT
NAME OF NOMINEE OF U.S. DEPOSITARY], HAS AN INTEREST HEREIN".

                                       14
<PAGE>

     "TRANSFERS OF THIS GLOBAL SECURITY SHALL BE LIMITED TO TRANSFERS IN WHOLE,
BUT NOT IN PART, TO NOMINEES OF [INSERT NAME OF U.S. DEPOSITARY] OR TO A
SUCCESSOR THEREOF OR SUCH SUCCESSOR'S NOMINEE AND TRANSFERS OF PORTIONS OF THIS
GLOBAL SECURITY SHALL BE LIMITED TO TRANSFERS MADE IN ACCORDANCE WITH THE
RESTRICTIONS SET FORTH IN SECTION 2.6 OF THE INDENTURE REFERRED TO ON THE
REVERSE HEREOF".

     Members of, or participants in, a U.S. Depositary ("Agent Members") shall
                                                         -------------
have no rights under this Indenture with respect to any Global Security held on
their behalf by the U.S. Depositary or under any Global Security, and the U.S.
Depositary may be treated by the Issuer, the Trustee, and any agent of the
Issuer or the Trustee as the absolute owner of such Global Security for all
purposes whatsoever. Notwithstanding the foregoing, nothing herein shall prevent
the Issuer, the Trustee or any agent of the Issuer or the Trustee from giving
effect to any written certification, proxy or other authorization furnished by
the U.S. Depositary or impair, as between the U.S. Depositary and its Agent
Members, the operation of customary practices governing the exercise of the
rights of a holder of any security.

               (ii) This Section 2.4(c)(ii) shall apply only to the Global
Security deposited on behalf of the purchasers of the Securities represented
thereby with the Trustee as custodian for the U.S. Depositary for credit to
their respective accounts (or to such other accounts as they may direct) at
Euroclear or Clearstream insofar as interests in the Global Security are held by
the Agent Members for Euroclear or Clearstream.

     The provisions of the "Operating Procedures of the Euroclear System" and
the "Terms and Conditions Governing Use of Euroclear" and the "Management
Regulations" and "Instructions to Participants" of Clearstream, respectively,
shall be applicable to such Global Security insofar as interests therein are
held by the Agent Members for Euroclear and Clearstream. Account holders or
participants in Euroclear and Clearstream shall have no rights under this
Indenture with respect to the Global Security, and the nominee of the U.S.
Depositary may be treated by the Issuer and the Trustee and any agent of the
Issuer or the Trustee as the owner of the Global Security for all purposes
whatsoever. Notwithstanding the foregoing, nothing herein shall prevent the
Issuer, the Trustee or any agent of the Issuer or the Trustee from giving effect
to any written certification, proxy or other authorization furnished by the U.S.
Depositary or impair, as between the U.S. Depositary and its Agent Members, the
operation of customary practices governing the exercise of the rights of a
holder of any security.

               (d)  Except as otherwise set forth in the related Series
Supplemental Indenture, each Security shall be dated the date of its
authentication and shall bear interest from the applicable date, and shall be
payable on the dates, specified on the face of the form of Security attached as
Exhibit A to the related Series Supplemental Indenture.

               (e)  The Person in whose name any Security of a series is
registered at the close of business on the record date specified in such
Securities with respect to any Interest Payment Date shall be entitled to
receive the interest, if any, payable on such Interest Payment Date
notwithstanding any transfer or exchange of such Security subsequent to the
record date and prior to such Interest Payment Date, except if and to the extent
the Issuer shall default in the

                                       15
<PAGE>

payment of the interest due on such Interest Payment Date, in which case such
defaulted interest shall be paid to the Persons in whose names Outstanding
Securities of such series are registered at the close of business on a
subsequent special record date, to be established (together with the related
payment date) by the Issuer with the consent of the Trustee. Such special record
date shall not be more than 15 nor less than 10 Business Days prior to the
payment date. Not more than 15 days prior to the special record date, the Issuer
(or the Trustee, in the name of and at the expense of the Issuer) shall mail to
Holders of such Securities a notice that states the special record date, the
related payment date and the amount of interest to be paid. Notice of the
proposed payment of such defaulted interest and the special record date therefor
having been mailed as aforesaid, such defaulted interest shall be paid to the
Persons in whose names such Securities are registered on such special record
date.

               (f)  The Securities shall be issuable in the denominations
specified in the form of Security attached as Exhibit A to the related Series
Supplemental Indenture.

     Section 2.5    Global Securities. (a) Portions of a Global Security
                    -----------------
deposited with the U.S. Depositary pursuant to Section 2.4 shall be transferred
in certificated form to the beneficial owners thereof only if such transfer
complies with Section 2.6 of this Indenture and (i) the U.S. Depositary notifies
the Issuer that it is unwilling or unable to continue as U.S. Depositary for
such Global Security or if at any time such U.S. Depositary ceases to be a
"clearing agency" registered under the Exchange Act and a successor depositary
 ---------------
is not appointed by the Issuer within 90 days of such notice, or (ii) an Event
of Default has occurred and is continuing with respect to the Securities and
payment of principal thereof and interest thereon has been accelerated.

               (b)  Portions of any Global Security that are transferable to the
beneficial owners thereof pursuant to this Section 2.5 shall be surrendered by
the U.S. Depositary to the Trustee at its New York office for registration of
transfer, in whole or from time to time in part, without charge, and the Trustee
shall authenticate and deliver, upon such registration of transfer of each
portion of such Global Security, an equal aggregate principal amount of
Securities of authorized denominations. Any portion of a Global Security whose
registration is transferred pursuant to this Section 2.5 shall be executed,
authenticated and delivered only in the denominations specified in the form of
Security attached as Exhibit A to the related Series Supplemental Indenture and
registered in such names as the U.S. Depositary shall direct. Any Security
delivered in exchange for a portion of the Rule 144A Global Security shall bear
the Legend regarding transfer restrictions applicable to the Rule 144A Global
Security set forth on the form of Security attached as Exhibit A to the related
Series Supplemental Indenture. Any Security delivered in exchange for a portion
of the IAI Global Security shall bear the Legend regarding transfer restrictions
set forth on the form of Security attached as Exhibit A to the related Series
Supplemental Indenture. Any Security delivered in exchange for a portion of the
Restricted or Unrestricted Regulation S Global Security shall bear the Legend
regarding transfer restrictions applicable to the Restricted or Unrestricted
Registration S Global Security, as the case may be, set forth on the form of
Security attached as Exhibit A to the related Series Supplemental Indenture.

               (c)  Subject to the provisions of Section 2.4(c) above, the
registered Holder of any Global Security may grant proxies and otherwise
authorize any person, including Agent

                                       16
<PAGE>

Members and persons that may hold interests through Agent Members, to take any
action which a Holder is entitled to take under this Indenture or such
Securities.

               (d)  In the event of the occurrence of any of the events
specified in paragraph (a) of this Section 2.5, the Issuer shall promptly make
available to the Trustee a reasonable supply of certificated Securities in
definitive fully registered form without interest coupons.

               (e)  The Global Security issued and authenticated pursuant to the
first paragraph of Section 2.4(b) (both before and after the expiration of the
restricted period), the Rule 144A Global Security and the IAI Global Security
shall each be assigned separate securities identification, or "CUSIP," numbers.
                                                               -----

     Section 2.6    Registration, Registration of Transfer and Exchange. (a) The
                    ---------------------------------------------------
Issuer shall keep at each office or agency to be maintained for the purpose as
provided in Section 3.2 hereof a register or registers (collectively referred to
as the "Securities Register") in which, subject to such reasonable regulations
        -------------------
as it may prescribe, it will register or cause to be registered, and will
register or cause to be registered the transfer of, Securities as in this
Article provided. Except as otherwise provided in a Series Supplemental
Indenture, the Issuer will be the "Security Registrar" for the purpose of
                                   ------------------
registering Securities and transfers of Securities as herein provided. Unless
the Trustee shall be serving as Security Registrar, such Securities Register
shall be open for inspection by the Trustee at all reasonable times.

     Upon due presentation for registration of transfer of any Security of a
series at each such office or agency, the Issuer shall execute and the Trustee
shall authenticate and deliver in the name of the transferee or transferees a
new Security or Securities of the same series in authorized denominations for a
like aggregate principal amount.

     Any Security or Securities of a series may be exchanged for a Security or
Securities of the same series in other authorized denominations, in an equal
aggregate principal amount. Securities of a series to be exchanged shall be
surrendered at each office or agency to be maintained by the Issuer for the
purpose as provided in Section 3.2 hereof, and the Issuer shall execute and the
Trustee shall authenticate and deliver in exchange therefor the Security or
Securities of the same series which the Holder making the exchange shall be
entitled to receive, bearing numbers not contemporaneously outstanding.

     All Securities presented for registration of transfer, exchange, redemption
or payment shall (if so required by the Issuer or the Trustee) be duly endorsed
by, or be accompanied by a written instrument or instruments of transfer in form
satisfactory to the Issuer and the Trustee duly executed by, the Holder or its
attorney duly authorized in writing.

     The Issuer or Trustee shall not be required to exchange or register a
transfer of (a) any Securities of a series for a period of 15 days next
preceding the first mailing of notice of redemption of Securities of the same
series to be redeemed or (b) any Securities selected, called or being called for
redemption except, in the case of any Security where public notice has been
given that such Security is to be redeemed in part, the portion thereof not so
to be redeemed.

                                       17
<PAGE>

     All Securities issued upon any registration of transfer or exchange of
Securities shall be valid obligations of the Issuer, evidencing the same debt,
and entitled to the same benefits under this Indenture, as the Securities
surrendered upon such registration of transfer or exchange.

               (b)  Notwithstanding any provision to the contrary herein, so
long as a Global Security remains outstanding and is held by or on behalf of the
U.S. Depositary, transfers of a Global Security, in whole or in part, shall only
be made (x) in the case of transfers of portions of a Global Security to
beneficial owners thereof in certificated form, in accordance with Section 2.5,
and (y) in all other cases, in accordance with this Section 2.6(b) (and subject,
in each case, to the provisions of any Legend (as defined herein) imprinted on
such Global Security).

                    (i)    Transfers of Global Securities as Such. Subject to
                           --------------------------------------
          clauses (ii) through (vi) of this Section 2.6(b), transfers of a
          Global Security shall be limited to transfers of such Global Security
          in whole, and not in part, to nominees of the U.S. Depositary or to a
          successor of the U.S. Depositary or such successor's nominee.

                    (ii)   Rule 144A Global Security or IAI Global Security to
                           ---------------------------------------------------
          Restricted Regulation S Global Security. If a holder of a beneficial
          ---------------------------------------
          interest in the Rule 144A Global Security of a series or the IAI
          Global Security of a series deposited with the U.S. Depositary wishes
          at any time to exchange or transfer its interest in such Global
          Security to a Person who wishes to take delivery thereof in the form
          of an interest in the Restricted Regulation S Global Security of the
          same series, such holder may, subject to the rules and procedures of
          the U.S. Depositary, exchange or transfer or cause the exchange or
          transfer of such interest for an equivalent beneficial interest in
          such Restricted Regulation S Global Security in accordance with, and
          subject to, this clause (ii). Upon receipt by the Trustee at the
          Corporate Trust Office of (1) instructions given in accordance with
          the U.S. Depositary's procedures from an Agent Member directing the
          Trustee to credit or cause to be credited a beneficial interest in
          such Restricted Regulation S Global Security in an amount equal to the
          beneficial interest in the Rule 144A Global Security of the same
          series or the IAI Global Security of the same series, as the case may
          be, to be exchanged or transferred, (2) a written order given in
          accordance with the U.S. Depositary's procedures containing
          information regarding the Euroclear or Clearstream account to be
          credited with such increase and the name of such account, and (3) a
          certificate in the form of Exhibit C attached to the related Series
          Supplemental Indenture given by the holder of such beneficial interest
          stating that the exchange or transfer of such interest has been made
          in compliance with the transfer restrictions applicable to the
          Securities of such series and pursuant to and in accordance with
          Regulation S, the Trustee shall instruct the U.S. Depositary to reduce
          the Rule 144A Global Security of such series or the IAI Global
          Security of such series, as the case may be, by the aggregate
          principal amount of the beneficial interest in the Rule 144A Global
          Security of such series or the IAI Global Security of such series, as
          the case may be, to be so exchanged or transferred and the Trustee
          shall instruct the U.S. Depositary, concurrently with such reduction,
          to increase the principal amount of the Restricted Regulation S Global
          Security of such series by the aggregate principal amount of the
          beneficial interest in the Rule 144A Global Security of such series or
          the IAI Global Security of such series, as the case may be, to be so
          exchanged or transferred, and to credit or cause to be credited to the
          account of the person specified in such instructions (who shall be the
          Agent Member for

                                       18
<PAGE>

          Euroclear or Clearstream, or both, as the case may be) a beneficial
          interest in the Restricted Regulation S Global Security of such series
          equal to the reduction in the principal amount of the Rule 144A Global
          Security of such series or the IAI Global Security of such series, as
          the case may be.

                    (iii)  Rule 144A Global Security or IAI Global Security to
                           ---------------------------------------------------
          Unrestricted Regulation S Global Security. If a holder of a beneficial
          -----------------------------------------
          interest in the Rule 144A Global Security of a series or the IAI
          Global Security of a series, as the case may be, deposited with the
          U.S. Depositary wishes at any time to exchange its interest in such
          Global Security for an interest in the Unrestricted Regulation S
          Global Security of the same series, or to transfer its interest in
          such Global Security to a Person who wishes to take delivery thereof
          in the form of an interest in the Unrestricted Regulation S Global
          Security of the same series, such holder may, subject to the rules and
          procedures of the U.S. Depositary, exchange or cause the exchange or
          transfer or cause the transfer of such interest for an equivalent
          beneficial interest in such Unrestricted Regulation S Global Security
          in accordance with, and subject to, this clause (iii). Upon receipt by
          the Trustee at the Corporate Trust Office of (1) instructions given in
          accordance with the U.S. Depositary's procedures from an Agent Member
          directing the Trustee to credit or cause to be credited a beneficial
          interest in such Unrestricted Regulation S Global Security in an
          amount equal to the beneficial interest in the Rule 144A Global
          Security of the same series or the IAI Global Security of the same
          series, as the case may be, to be exchanged or transferred, (2) a
          written order given in accordance with the U.S. Depositary's
          procedures containing information regarding the participant account of
          the U.S. Depositary and, in the case of a transfer pursuant to and in
          accordance with Regulation S, the Euroclear or Clearstream account to
          be credited with such increase and (3) a certificate in the form of
          Exhibit D attached to the related Series Supplemental Indenture given
          by the holder of such beneficial interest stating that the exchange or
          transfer of such interest has been made in compliance with the
          transfer restrictions applicable to the Securities and (A) in the case
          of an exchange, that either (x) the Security being exchanged is not a
          "restricted security" as defined in Rule 144 under the Securities Act,
           -------------------
          or (y) the exchange is being made to facilitate a contemporaneous
          transfer that complies with this clause (iii), (B) in the case of a
          transfer pursuant to Regulation S, that the Security is being
          transferred pursuant to and in accordance with Regulation S, (C) in
          the case of a transfer pursuant to Rule 144, that the Security is
          being transferred pursuant to and in accordance with Rule 144 or (D)
          in the case of a transfer pursuant to another exemption from the
          Securities Act (including without limitation Rule 144A), specifying
          the basis for such exemption, the Trustee shall instruct the U.S.
          Depositary to reduce the Rule 144A Global Security of such series or
          the IAI Global Security of such series, as the case may be, by the
          aggregate principal amount of the beneficial interest in the Rule 144A
          Global Security of such series or the IAI Global Security of such
          series, as the case may be, to be so exchanged or transferred and the
          Trustee shall instruct the U.S. Depositary, concurrently with such
          reduction, to increase the principal amount of the Unrestricted
          Regulation S Global Security of such series by the aggregate principal
          amount of the beneficial interest in the Rule 144A Global Security of
          such series or the IAI Global Security of such series, as the case may
          be, to be so exchanged or transferred, and to credit or cause to be
          credited to the account of the person specified in such instructions a
          beneficial interest in the Unrestricted Regulation S Global Security
          of such

                                       19
<PAGE>

          series equal to the reduction in the principal amount of the Rule 144A
          Global Security of such series or the IAI Global Security of such
          series, as the case may be.

                    (iv)   Restricted Regulation S Global Security, Unrestricted
          Regulation S Global Security or IAI Global Security to Rule 144A
          Global Security. If a holder of a beneficial interest in the
          Restricted Regulation S Global Security of a series, the Unrestricted
          Regulation S Global Security of a series or the IAI Global Security of
          a series deposited with the U.S. Depositary wishes at any time to
          exchange or transfer its interest in such Restricted Regulation S
          Global Security, Unrestricted Regulation S Global Security or IAI
          Global Security to a Person who wishes to take delivery thereof in the
          form of an interest in the Rule 144A Global Security of the same
          series such holder may, subject to the rules and procedures of
          Euroclear or Clearstream and the U.S. Depositary, as the case may be,
          exchange or transfer or cause the exchange or transfer of such
          interest for an equivalent beneficial interest in such Rule 144A
          Global Security, in accordance with, and subject to, this clause (iv).
          Upon receipt by the Trustee, at the Corporate Trust Office of (1)
          instructions from Euroclear or Clearstream or the U.S. Depositary, as
          the case may be, directing the Trustee to credit or cause to be
          credited a beneficial interest in the such 144A Global Security equal
          to the beneficial interest in the Restricted Regulation S Global
          Security of the same series, the Unrestricted Regulation S Global
          Security of the same series or the IAI Global Security of the same
          series to be exchanged or transferred, such instructions to contain
          information regarding the Agent Member's account with the U.S.
          Depositary to be credited with such increase, and, with respect to an
          exchange or transfer of an interest in the Unrestricted Regulation S
          Global Security of the same series, information regarding the Agent
          Member's account with the U.S. Depositary to be debited with such
          decrease, and (2) a certificate in the form of Exhibit E attached to
          the related Series Supplemental Indenture given by the holder of such
          beneficial interest and stating that the person exchanging or
          transferring such interest in such Restricted Regulation S Global
          Security, the Unrestricted Regulation S Global Security or the IAI
          Global Security, as the case may be, reasonably believes that the
          person acquiring such interest in such Rule 144A Global Security is a
          qualified institutional buyer (as defined in Rule 144A) and is
          obtaining such beneficial interest in a transaction meeting the
          requirements of Rule 144A, Euroclear or Clearstream or the Trustee, as
          the case may be, shall instruct the U.S. Depositary to reduce the
          Restricted Regulation S Global Security of such series, the
          Unrestricted Regulation S Global Security of such series or the IAI
          Global Security of such series, as the case may be, by the aggregate
          principal amount of the beneficial interest in the Restricted
          Regulation S Global Security of such series, the Unrestricted
          Regulation S Global Security of such series or the IAI Global Security
          of such series to be exchanged or transferred, and the Trustee shall
          instruct the U.S. Depositary, concurrently with such reduction to
          increase the principal amount of the Rule 144A Global Security of such
          series by the aggregate principal amount of the beneficial interest in
          the Restricted Regulation S Global Security of such series, the
          Unrestricted Regulation S Global Security of such series or the IAI
          Global Security of such series, as the case may be, to be so exchanged
          or transferred, and to credit or cause to be credited to the account
          of the person specified in such instructions a beneficial interest in
          the Rule 144A Global Security of such series equal to the reduction in
          the principal amount of the Restricted Regulation S Global Security of
          such

                                       20
<PAGE>

          series, the Unrestricted Regulation S Global Security of such series
          or the IAI Global Security of such series, as the case may be.

                    (v)    Rule 144A Global Security, Restricted Regulation S
          Global Security or Unrestricted Regulation S Global Security to IAI
          Global Security. If a holder of a beneficial interest in the Rule 144A
          Global Security of a series, the Restricted Regulation S Global
          Security of a series or the Unrestricted Regulation S Global Security
          of a series deposited with the U.S. Depositary wishes at any time to
          exchange or transfer its interest in such Global Security to a Person
          who wishes to take delivery thereof in the form of an interest in the
          IAI Global Security of the same series such holder may, subject to the
          rules and procedures of Euroclear or Clearstream and the U.S.
          Depositary, as the case may be, exchange or transfer or cause the
          exchange or transfer of such interest for an equivalent beneficial
          interest in such IAI Global Security, in accordance with, and subject
          to, this clause (v). Upon receipt by the Trustee, at the Corporate
          Trust Office of (1) instructions from Euroclear or Clearstream or the
          U.S. Depositary, as the case may be, directing the Trustee to credit
          or cause to be credited a beneficial interest in such IAI Global
          Security equal to the beneficial interest in the Restricted Regulation
          S Global Security of the same series, the Unrestricted Regulation S
          Global Security of the same series or the Rule 144A Global Security of
          the same series to be exchanged or transferred, such instructions to
          contain information regarding the Agent Member's account with the U.S.
          Depositary to be credited with such increase, and, with respect to an
          exchange or transfer of an interest in the Unrestricted Regulation S
          Global Security of the same series, information regarding the Agent
          Member's account with the U.S. Depositary to be debited with such
          decrease, and (2) a certificate in the form of Exhibit F attached to
          the related Series Supplemental Indenture given by the holder of such
          beneficial interest and stating that the person exchanging or
          transferring such interest reasonably believes that the person
          acquiring such interest in such IAI Global Security is an institution
          that is an "accredited investor" (as defined in Rule 501(a)(1), (2),
          (3) or (7) under the Securities Act) and is obtaining such beneficial
          interest in a transaction exempt from the Securities Act, Euroclear or
          Clearstream or the Trustee, as the case may be, shall instruct the
          U.S. Depositary to reduce the Restricted Regulation S Global Security
          of such series, the Unrestricted Regulation S Global Security of such
          series or the Rule 144A Global Security of such series, as the case
          may be, by the aggregate principal amount of the beneficial interest
          in such Global Securities to be exchanged or transferred, and the
          Trustee shall instruct the U.S. Depositary, concurrently with such
          reduction to increase the principal amount of the IAI Global Security
          of such series by the aggregate principal amount of the beneficial
          interest in the Restricted Regulation S Global Security of such
          series, the Unrestricted Regulation S Global Security of such series
          or the Rule 144A Global Security of such series, as the case may be,
          to be so exchanged or transferred, and to credit or cause to be
          credited to the account of the person specified in such instructions a
          beneficial interest in the IAI Global Security of such series equal to
          the reduction in the principal amount of the Restricted Regulation S
          Global Security of such series, the Unrestricted Regulation S Global
          Security of such series or the Rule 144A Global Security of such
          series, as the case may be.

                    (vi)   Other Exchanges. In the event that a Global Security
          of a series is exchanged for Securities of the same series in
          definitive registered form without interest

                                       21
<PAGE>

          coupons pursuant to Section 2.5 hereof, such Securities may be
          exchanged or transferred for one another only in accordance with such
          procedures as are substantially consistent with the provisions of
          clauses (ii) through (v) above (including, without limitation, the
          certification requirements intended to insure that such exchanges or
          transfers comply with Rule 144A, Rule 144 or Regulation S under and
          generally with the Securities Act, as the case may be) and as may be
          from time to time adopted by the Issuer and the Trustee.

               (c)  Successive registrations and registrations of transfers and
exchanges as aforesaid may be made from time to time as desired, and each such
registration shall be noted on the Security Register. No service charge shall be
made for any registration of transfer or exchange of the Securities, but the
Trustee may require payment of a sum sufficient to cover any tax or other
governmental charge payable in connection therewith and any other amounts
required to be paid by the provisions of the Securities.

               (d)  If Securities are issued upon the registration of transfer,
exchange or replacement of Securities not bearing the legends required by the
form of Security attached as Exhibit A to the related Series Supplemental
Indenture (collectively, the "Legend"), the Securities so issued shall bear the
                              ------
Legend. If Securities are issued upon the registration of transfer, exchange or
replacement of Securities bearing the Legend, or if a request is made to remove
the Legend on a Security, the Securities so issued shall bear the Legend, or the
Legend shall not be removed, as the case may be, unless there is delivered to
the Issuer and the Trustee such satisfactory evidence, which may include an
opinion of counsel of recognized standing licensed to practice law in the State
of New York and experienced in matters involving the Securities Act, as may be
reasonably required by the Issuer that neither the Legend nor the restrictions
on transfer set forth therein are required to ensure that transfers thereof
comply with the provisions of Rule 144A, Rule 144 or Regulation S under the
Securities Act or that such Securities are not "restricted securities" within
                                                ---------------------
the meaning of Rule 144 under the Securities Act. Upon provision of such
satisfactory evidence, the Trustee, at the direction of the Issuer, shall
authenticate and deliver a Security that does not bear the Legend. If a legend
is removed from the face of a Security and the Security is subsequently held by
an affiliate of the Issuer, the Legend shall be reinstated. Notwithstanding the
foregoing, neither the Legend nor any restrictions on transferability contained
herein shall apply to the Exchange Notes.

     Section 2.7    Mutilated, Defaced, Destroyed, Lost and Stolen Securities.
                    ---------------------------------------------------------
In case any temporary or definitive Security shall become mutilated, defaced or
be apparently destroyed, lost or stolen, the Issuer in its discretion may
execute, and upon the written request of any officer of the Issuer, the Trustee
shall authenticate and deliver a new Security of the same series, bearing a
number not contemporaneously outstanding, in exchange and substitution for the
mutilated or defaced Security, or in lieu of and substitution for the Security
so apparently destroyed, lost or stolen. In every case the applicant for a
substitute Security shall furnish to the Issuer and to the Trustee and any agent
of the Issuer or the Trustee such security or indemnity as may be required by
them to indemnify and defend and to save each of them harmless and, in every
case of destruction, loss or theft, evidence to their satisfaction of the
apparent destruction, loss or theft of such Security and of the ownership
thereof.

     Upon the issuance of any substitute Security, the Issuer may require
the payment of a sum sufficient to cover any tax or other governmental charge
that may be imposed in relation

                                       22
<PAGE>

thereto and any other expenses (including the fees and expenses of the Trustee)
connected therewith. In case any Security which has matured or is about to
mature, or has been called for redemption in full, shall become mutilated or
defaced or be apparently destroyed, lost or stolen, the Issuer may, instead of
issuing a substitute Security, pay or authorize the payment of the same (without
surrender thereof except in the case of a mutilated or defaced Security), if the
applicant for such payment shall furnish to the Issuer and to the Trustee and
any agent of the Issuer or the Trustee such security or indemnity as any of them
may require to save each of them harmless from all risks, however remote, and,
in every case of apparent destruction, loss or theft, the applicant shall also
furnish to the Issuer and the Trustee and any agent of the Issuer or the Trustee
evidence to their satisfaction of the apparent destruction, loss or theft of
such Security and of the ownership thereof.

     Every substitute Security issued pursuant to the provisions of this
Section by virtue of the fact that any Security is apparently destroyed, lost or
stolen shall constitute an additional contractual obligation of the Issuer,
whether or not the apparently destroyed, lost or stolen Security shall be at any
time enforceable by anyone and shall be entitled to all the benefits of (but
shall be subject to all the limitations of rights set forth in) this Indenture
equally and proportionately with any and all other Securities duly authenticated
and delivered hereunder. All Securities shall be held and owned upon the express
condition that, to the extent permitted by law, the foregoing provisions are
exclusive with respect to the replacement or payment of mutilated, defaced, or
apparently destroyed, lost or stolen Securities and shall preclude any and all
other rights or remedies notwithstanding any law or statute existing or
hereafter enacted to the contrary with respect to the replacement or payment of
negotiable instruments or other securities without their surrender.

     Section 2.8   Cancellation of Securities; Destruction Thereof. All
                   -----------------------------------------------
Securities surrendered for payment, redemption, registration of transfer or
exchange, if surrendered to the Issuer or any agent of the Issuer or the
Trustee, shall be delivered to the Trustee for cancellation or, if surrendered
to the Trustee, shall be canceled by it provided all conditions regarding such
cancellation have been met; and no Securities shall be issued in lieu thereof
except as expressly permitted by any of the provisions of this Indenture. The
Trustee shall cancel and dispose of all Securities surrendered for registration
of transfer, exchange, payment or cancellation in accordance with the Trustee's
policy of disposal unless the Issuer instructs the Trustee in writing to deliver
the Securities to the Issuer. If the Issuer shall acquire any of the Securities,
such acquisition shall not operate as a redemption or satisfaction of the
indebtedness represented by such Securities unless and until the same are
delivered to the Trustee for cancellation.

     Section 2.9   Temporary Securities. Pending the preparation of definitive
                   --------------------
Securities of any series, the Issuer may execute and the Trustee shall
authenticate and deliver temporary Securities of such series (printed,
lithographed, typewritten or otherwise reproduced, in each case in form
satisfactory to the Trustee). Temporary Securities of any series shall be
issuable as registered Securities of such series without coupons, of any
authorized denomination, and substantially in the form of the definitive
Securities of such series but with such omissions, insertions and variations as
may be appropriate for temporary Securities of such series, all as may be
determined by the Issuer with the concurrence of the Trustee. Temporary
Securities of such series may contain such reference to any provisions of this
Indenture as may be appropriate. Every temporary Security of any series shall be
executed by the Issuer and be authenticated by

                                       23
<PAGE>

the Trustee upon the same conditions and in substantially the same manner, and
with like effect, as the definitive Securities of such series. Without
unreasonable delay the Issuer shall execute and shall furnish definitive
Securities of any series and thereupon temporary Securities of such series may
be surrendered in exchange therefor without charge at each office or agency to
be maintained by the Issuer for the purpose pursuant to Section 3.2 hereof, and
the Trustee shall authenticate and deliver in exchange for such temporary
Securities of any series a like aggregate principal amount of definitive
Securities of such series of authorized denominations. Until so exchanged the
temporary Securities of any series shall be entitled to the same benefits under
this Indenture as definitive Securities of such series.

     Section 2.10  Computation of Interest. Except as otherwise set forth in a
                   -----------------------
Series Supplemental Indenture relating to a series of Securities, interest on
the Securities shall be computed on the basis of a 360-day year of twelve 30-day
months.

                                  ARTICLE III

                    COVENANTS OF THE ISSUER AND THE TRUSTEE
                    ---------------------------------------

     Section 3.1   Payment of Principal and Interest. The Issuer covenants and
                   ---------------------------------
agrees that it will duly and punctually pay or cause to be paid the principal
of, and premium, if any, and interest on, each of the Securities of each series
at the place or places, at the respective times and in the manner provided in
the Securities of such series. Except as otherwise provided in a Series
Supplemental Indenture, payment of principal of, and premium and interest on the
Securities of each series shall be paid by mailing a check to or upon the
written order of the registered Holders of such Securities entitled thereto at
their last address as it appears on the Securities Register or, upon written
application to the Issuer and the Trustee by a Holder of $1,000,000 or more in
aggregate principal amount of Securities of a series, by wire transfer of
immediately available funds to an account maintained by such Holder with a bank
or other financial institution; provided, however, that (subject to the
                                --------  -------
provisions of Section 2.7 hereof) payment of principal of, and premium, if any,
on, any Security of a series may be conditioned upon presentation for payment of
the certificate representing such Security.

     Section 3.2   Offices for Payments, etc. So long as any of the Securities
                   -------------------------
remain Outstanding, the Issuer shall maintain in St. Louis, Missouri, the
following: (a) an office or agency where the Securities may be presented for
payment, (b) an office or agency where the Securities may be presented for
registration of transfer and for exchange as in this Indenture provided and (c)
an office or agency where notices and demands to or upon the Issuer in respect
of the Securities or of this Indenture may be served. The Issuer shall give to
the Trustee written notice of the location of any such office or agency and of
any change of location thereof. The Issuer hereby initially designates its
office at the location set forth in Section 10.4 as such office or agency. In
case the Issuer shall fail to maintain any such office or agency or shall fail
to give such notice of the location or of any change in the location thereof,
presentations and demands may be made and notices may be served at the Corporate
Trust Office.

     Section 3.3   Appointment to Fill a Vacancy in Office of Trustee. The
                   --------------------------------------------------
Issuer, whenever necessary to avoid or fill a vacancy in the office of Trustee,
shall appoint, in the manner provided in Section 5.9 hereof, a Trustee, so that
there shall at all times be a Trustee hereunder.

                                       24
<PAGE>

     Section 3.4   Paying Agents. Except as otherwise set forth in a Series
                   -------------
Supplemental Indenture relating to the Securities of a series, the Issuer shall
be the principal paying agent for the Securities. Whenever the Issuer shall
appoint a paying agent other than itself or the Trustee, it shall cause such
paying agent to execute and deliver to the Trustee an instrument in which such
agent shall agree with the Trustee, subject to the provisions of this Section:

               (a) that it will hold all sums received by it as such agent for
the payment of the principal of, or premium or interest on, the Securities of
any series (whether such sums have been paid to it by the Issuer or by any other
obligor on the Securities of such series) in trust for the benefit of the
Holders of the Securities of such series or of the Trustee,

               (b) that it will give the Trustee notice of any failure by the
Issuer (or by any other obligor on the Securities) to make any payment of the
principal of, or premium or interest on, the Securities when the same shall be
due and payable, and

               (c) pay any such sums so held in trust by it to the Trustee upon
the Trustee's written request at any time during the continuance of the failure
referred to in clause (b) above.

The Issuer shall, prior to each due date of the principal of, and premium, if
any, or interest on the Securities of a series, deposit with the paying agent a
sum sufficient to pay such principal, premium or interest, and (unless such
paying agent is the Trustee) the Issuer shall promptly notify the Trustee of any
failure to take such action.

     Anything in this Section 3.4 to the contrary notwithstanding, the Issuer
may at any time, for the purpose of obtaining a satisfaction and discharge of
this Indenture or for any other reason, pay or cause to be paid to the Trustee
all sums held in trust by any paying agent hereunder, as required by this
Section 3.4, such sums to be held by the Trustee upon the trusts herein
contained.

     Anything in this Section to the contrary notwithstanding, the agreement to
hold sums in trust as provided in this Section 3.4 is subject to the provisions
of Section 9.3 and Section 9.4 hereof.

     Section 3.5   Reports by the Trustee.
                   ----------------------

               (a) Within 60 days after April 15 of each year commencing with
the year 2001, the Trustee shall transmit by mail to all Holders of Securities,
a brief report dated as of such date if and to the extent required under Section
313(a) of the Trust Indenture Act .

               (b) The Trustee shall comply with Sections 313(b) and 313(c) of
the Trust Indenture Act.

               (c) A copy of each report described in Section 3.5(a) or referred
to in Section 3.5(b) shall, at the time of its transmission to Holders, be filed
by the Trustee with each securities exchange, if any, upon which the Securities
are then listed, with the Commission and also with the Issuer. The Issuer shall
promptly notify the Trustee of any securities exchange upon which the Securities
are listed.

                                       25
<PAGE>

     Section 3.6   Holders' Lists.
                   --------------

               (a) The Issuer shall furnish or cause to be furnished to the
Trustee a list in such form as the Trustee may reasonably require of all
information in the possession of the Issuer or any paying agent, as to the names
and addresses of the Holders of the Securities (i) semiannually not more than 15
days after each record date for the payment of semi-annual interest on the
Securities, as specified in the form of Security attached as Exhibit A to the
related Series Supplemental Indenture, as of such record date and (ii) at other
times as the Trustee may request in writing, within thirty days after receipt by
the Issuer of any such request as of a date not more than 15 days prior to the
time such information is furnished. The Trustee shall preserve, in as current a
form as is reasonably practicable, the names and addresses of Holders contained
in the most recent list furnished to the Trustee as provided in this Section 3.6
and the names and addresses of Holders received by the Trustee in its capacity
as paying agent, if so acting.

               (b) Within five business days after receipt by the Trustee of a
written application by any three or more Holders stating that such applicants
desire to communicate with other Holders with respect to their rights under the
Indenture or under the Securities, and accompanied by a copy of the form of
proxy or other communication which such applicants propose to transmit, and by
reasonable proof that each such applicant has owned a Security for a period of
at least six months preceding the date of such application, the Trustee shall,
at its election, either:

                   (i)   afford to such applicants access to all information so
     furnished to or received by the Trustee under Section 3.6(a); or

                   (ii)  inform such applicants as to the approximate number of
     Holders according to the most recent information so furnished to or
     received by the Trustee, and as to the approximate cost of mailing to such
     Holders the form of proxy or other communication, if any, specified in such
     application.

                   If the Trustee shall elect not to afford to such applicants
access to such information, the Trustee shall, upon the written request of such
applicants, mail to all Holders copies of the form of proxy or other
communication which is specified in such request, with reasonable promptness
after a tender to the Trustee of the material to be mailed and of payment, or
provision for the payment, of the reasonable expenses of such mailing, unless
within five days after such tender, the Trustee shall mail to such applicants,
and file with the Commission together with a copy of the material to be mailed,
a written statement to the effect that, in the opinion of the Trustee, such
mailing would be contrary to the best interests of the Holders or would be in
violation of applicable law. Such written statement shall specify the basis of
such opinion. If the Commission, after opportunity for hearing upon the
objections specified in the written statement so filed, shall enter an order
refusing to sustain any of such objections or if, after the entry of an order
sustaining one or more of such objections, the Commission shall find, after
notice and opportunity for hearing, that all the objections so sustained have
been met and shall enter an order so declaring, the Trustee shall mail copies of
such material to all Holders with reasonable promptness after the entry of such
order and the renewal of such tender.

                                       26
<PAGE>

               (c) Each Holder of Securities, by receiving and holding the same,
agrees with the Issuer and the Trustee that neither the Issuer nor the Trustee
shall be held accountable by reason of the disclosure of any such information as
to the names and addresses of the Holders in accordance with this Section 3.6,
regardless of the source from which such information was derived, and that the
Trustee shall not be held accountable by reason of mailing any material pursuant
to a request made under this Section 3.6.

     Section 3.7   Reports by the Issuer. (a) The Issuer shall furnish to the
                   ---------------------
Trustee: (i) unless the Issuer is then filing comparable reports pursuant to the
reporting requirements of the Exchange Act, as soon as practicable and in any
event within 45 days after the end of each of the first, second and third
quarterly accounting periods of each fiscal year of the Issuer (commencing with
the quarter ending September 30, 2000), an unaudited consolidated balance sheet
of the Issuer as of the last day of such quarterly period and the related
consolidated statements of income and cash flows during such quarterly period
prepared in accordance with GAAP and (in the case of second and third quarterly
periods) for the portion of the fiscal year ending with the last day of such
quarterly period, setting forth in each case in comparative form corresponding
unaudited figures from the preceding fiscal year (except in the case where the
preceding fiscal year includes periods prior to the formation of the Issuer) and
accompanied by (A) a written statement of the Controller, any Vice President or
the Treasurer of the Issuer to the effect that such financial statements fairly
represent the Issuer's financial condition and results of operations at and as
of their respective dates, (B) a section substantially similar to the
"Management's Discussion and Analysis" ("MD&A") section of a Commission Form
10-Q (without any comparison to periods prior to the formation of the Issuer),
and (C) a calculation of the Senior Debt Service Coverage Ratio for the prior
four quarterly periods (or the number of complete quarterly periods since July
1, 2000); (ii) unless the Issuer is then filing comparable reports pursuant to
the reporting requirements of the Exchange Act, as soon as practicable and in
any event within 90 days after the end of each fiscal year of the Issuer
(commencing with the fiscal year ending December 31, 2000), a consolidated
balance sheet of the Issuer as of the end of such year and the related
consolidated statements of income, cash flow, and retained earnings during such
year setting forth in each case in comparative form corresponding figures from
the preceding fiscal year (except in the case where the preceding fiscal year
includes periods prior to the formation of the Issuer), accompanied by (A) an
audit report thereon of a firm of independent public accountants of recognized
national standing, (B) a section substantially similar to the MD&A section of a
Commission Form 10-K (without any comparison to periods prior to the formation
of the Issuer), and (C) a calculation of the Senior Debt Service Coverage Ratio
for the prior four quarterly periods (or the number of complete quarterly
periods since July 1, 2000); (iii) at the time of the delivery of the report
provided for in clause (ii) above (or at the time of the filing of the
comparable report pursuant to the Exchange Act), an officer's certificate to the
effect that, to the best of such officer's knowledge, no default or Event of
Default under the Securities of any series or the Indenture has occurred and is
continuing or, if any default or Event of Default thereunder has occurred and is
continuing, specifying the nature and extent thereof and what action the Issuer
is taking or proposes to take in response thereto; and (iv) promptly after it
obtains actual knowledge of the occurrence thereof, written notice of the
occurrence of any event or condition which constitutes an Event of Default, and
an officer's certificate of the Issuer specifically stating that such Event of
Default has occurred and setting forth the details thereof and the action which
the Issuer is taking or proposes to take with respect thereto. The calculation
required by (i)(C) and (ii)(C) shall be furnished to the Trustee within the time
period provided

                                       27
<PAGE>

therefor unless the Issuer is then including such information in comparable
reports filed pursuant to the reporting requirements of the Exchange Act.

               (b) Upon the request of any Holder, any holder of a beneficial
interest in the Securities of any series, or the Trustee (on behalf of a Holder
or a holder of a beneficial interest in the Securities of any series), the
Issuer shall furnish such information as is specified in paragraph (d)(4) of
Rule 144A to Holders (and holders of beneficial interests in the Securities of
any series), prospective purchasers of the Securities of any series (and
prospective purchasers of beneficial interests in the Securities of any series)
who are qualified institutional buyers or institutional accredited investors or
to the Trustee for delivery to such Holder or prospective purchasers of the
Securities of any series or beneficial interests therein, as the case may be,
unless, at the time of such request, the Issuer is subject to the reporting
requirements of Section 13 or 15(d) of the Exchange Act.

               (c) All such information provided to the Trustee pursuant to
paragraphs (a)(i), (a)(ii), (a)(iii) and (a)(iv) above also shall be provided by
the Trustee upon written request to the Trustee (which may be a single
continuing request), to (x) Holders, (y) holders of beneficial interests in the
Securities of any series or (z) prospective purchasers of the Securities of any
series or beneficial interests in the Securities of any series. The Issuer shall
furnish the Trustee, upon its request, sufficient copies of all such information
to accommodate the requests of such holders and prospective holders of
beneficial interests in the Securities of any series.

               (d) The information specified in paragraph (a) above shall be
provided by the Issuer to Moody's Investors Service, Inc., Standard & Poor's
Ratings Services and Fitch, Inc. concurrently with its delivery to the Trustee.

     Section 3.8   Limitation on Liens. The Issuer shall not, and shall not
                   -------------------
permit any of its Subsidiaries to, issue, assume, guarantee or permit to exist
any Indebtedness secured by any lien on any property of the Issuer or its
Subsidiaries, whether owned at the date of issuance of any Security or
thereafter acquired, without in any such case effectively securing the
Outstanding Securities (together with, if the Issuer shall so determine, any
other Indebtedness of or guaranteed by the Issuer ranking equally with the
Securities) equally and ratably with such Indebtedness (but only so long as such
Indebtedness is so secured); provided, however, that the foregoing restriction
                             --------  -------
shall not apply to the following liens: (i) pledges or deposits in the ordinary
course of business in connection with bids, tenders, contracts or statutory
obligations or to secure surety or performance bonds, (ii) liens imposed by law,
such as carriers', warehouseman's and mechanics' liens, arising in the ordinary
course of business, (iii) liens for property taxes being contested in good
faith, (iv) minor encumbrances, easements or reservations which do not in the
aggregate materially adversely affect the value of the properties or impair
their use, (v) liens on any property existing at the time of acquisition thereof
(which liens may also extend to subsequent repairs, alterations and improvements
to such property), (vi) liens to secure purchase money Indebtedness not in
excess of the cost or value of the property acquired, (vii) liens, if any, in
existence on the date of this Indenture, (viii) other liens to secure
Indebtedness so long as the amount of outstanding Indebtedness secured by liens
pursuant to this provision does not exceed 10% of Consolidated Tangible Assets,
and (ix) liens granted in connection with extending, renewing, replacing or
refinancing any of the Indebtedness (so long as there is no increase in the

                                       28
<PAGE>

principal amount of the Indebtedness), described in the foregoing clauses (v)
through (viii) above.

     In the event that the Issuer shall propose to pledge, mortgage or
hypothecate any property at any time directly owned by it to secure any
Indebtedness, other than as permitted by clauses (i) through (ix) of the
previous paragraph, the Issuer shall (prior thereto) give written notice thereof
to the Trustee, who shall give notice to the Holders, and the Issuer shall,
prior to or simultaneously with such pledge, mortgage or hypothecation,
effectively secure all the Securities equally and ratably with such
Indebtedness.

     Section 3.9   Limitations on Subsidiary Indebtedness. The Issuer shall not
                   --------------------------------------
permit any Subsidiary which may acquire any Initial Generation Assets to create
or incur or suffer to exist any Indebtedness for borrowed money.

     Section 3.10  Covenant Not to Merge, Consolidate, Sell or Transfer Assets
                   -----------------------------------------------------------
Except Under Certain Conditions. (a) The Issuer shall not consolidate with or
-------------------------------
merge with or into any other Person, or sell, convey, transfer or lease its
properties and assets substantially as an entirety to any Person, and the Issuer
shall not permit any Person to consolidate with or merge with or into the
Issuer, unless: (i) immediately prior to and immediately following such
consolidation, merger, sale or lease, no Event of Default shall have occurred
and be continuing and (ii) the Issuer is the surviving or continuing
corporation, or the surviving or continuing corporation or corporation that
acquires by sale, conveyance, transfer or lease is incorporated in the United
States of America or and expressly assumes the payment and performance of all
obligations of the Issuer under the Indenture and the Securities.

               (b) Except for the sale of the properties and assets of the
Issuer substantially as an entirety pursuant to subsection (a) above, and other
than assets required to be sold to conform with governmental regulations, the
Issuer shall not, and shall not permit any of its Subsidiaries to, consummate
any Asset Sale, if the aggregate net book value of all such Asset Sales
consummated since the date of the Indenture would exceed 25% of the Issuer's
Consolidated Tangible Assets as of the beginning of the Issuer's most recently
ended full fiscal quarter; provided, however, that any such Asset Sale will be
disregarded for purposes of the 25% limitation specified above if the proceeds
thereof (i) are, within 12 months of such Asset Sale, invested or reinvested by
the Company or any Subsidiary in a Permitted Business, (ii) are used by the
Company or a Subsidiary to repay Indebtedness of the Company or such Subsidiary,
or (iii) are retained by the Company or its Subsidiaries. Additionally, if,
after giving effect to any Asset Sale that otherwise would cause the 25%
limitation to be exceeded, each Rating Agency then rating any of the Securities
confirms the then current rating of such Securities, the portion of such Asset
Sale in excess of the 25% limitation shall also be disregarded for purposes of
the foregoing limitations.

     Section 3.11  Restricted Payments. (a) The Issuer shall not make any
                   -------------------
Restricted Payment unless, on a Pro Forma Basis at the time such Restricted
Payment is to be made, (a) the Senior Debt Service Coverage Ratio shall equal at
least 1.75 to 1.0 for the most recently ended four full fiscal quarters, or such
shorter period (of not less than one full fiscal quarter) commencing on July 1,
2000 and ending on the last day of the most recent fiscal quarter for which
financial statements have been delivered to the Trustee and (b) based on
projections

                                       29
<PAGE>

prepared by the Issuer on a reasonable basis, the projected Senior Debt Service
Coverage Ratio for each of the succeeding four six-month periods (commencing
with the month in which such distribution is to be made) or, with respect to any
date within the 24-month period prior to the final maturity date for the
Securities, the number of complete six-month periods, if any, until such final
maturity date for the Securities, in each case measured as individual six-month
periods, is projected to be greater than or equal to 1.75 to 1: provided,
however, that for any period in respect of which such projected Senior Debt
Service Coverage Ratio is calculated pursuant to this clause (b) for which
two-thirds or more of revenues are derived directly or indirectly from contracts
with AmerenCIPS, AmerenUE or non-affiliated third-parties and which have a then
remaining term of two years or more, such ratio shall be greater than or equal
to 1.50 to 1.0. The Issuer agrees that each payment of principal on the
Subordinated CIPS Note other than at final maturity is payable solely to the
extent Available Cash is available to make such payment.

     Section 3.12  Debt Incurrence Test. The Issuer shall not incur any
                   --------------------
Indebtedness other than Permitted Indebtedness for borrowed money unless on a
Pro Forma Basis for the debt incurrence and any related transactions either (i)
(a) the Senior Debt Service Coverage Ratio shall equal at least 2.5 to 1.0 for
the most recently ended four full fiscal quarters, or such shorter period (of
not less than one full fiscal quarter) commencing on July 1, 2000 and ending on
the last day of the most recent fiscal quarter for which financial statements
have been delivered to the Trustee and (b) the Issuer's Senior Debt to Capital
Ratio shall not exceed 0.6 to 1.0 or (ii) each Rating Agency then rating the
Securities of each series provides a Ratings Reaffirmation of the then existing
rating of such Securities after giving effect to such additional Indebtedness.

     Section 3.13  Termination of Financial Covenants. At any time following the
                   ----------------------------------
date on which financial statements for five full years of operations of the
Issuer are available, the Issuer may cease to comply with the covenants
specified in Sections 3.11 and 3.12 herein, if each rating agency then rating
the Outstanding Securities of each series provides to the Issuer and the Trustee
a Ratings Reaffirmation of at least the rating in effect on the Original Issue
Date of such Securities after giving effect to such fact, in which case, from
and after the date of such reaffirmation such covenants shall be deemed to be of
no further force and effect.

                                  ARTICLE IV

            REMEDIES OF THE TRUSTEE AND HOLDERS ON EVENT OF DEFAULT
            -------------------------------------------------------

     Section 4.1   Event of Default Defined; Acceleration of Maturity; Waiver of
                   -------------------------------------------------------------
Default. In case one or more of the following Events of Default (whatever the
-------
reason for such Event of Default and whether it shall be voluntary or
involuntary or be effected by operation of law or pursuant to any judgment,
decree or order of any court or any order, rule or regulation of any
administrative or governmental body) shall have occurred and be continuing, that
is to say:

               (a) default in the payment of all or any part of the principal
of, or premium, if any, on, any of the Securities as and when the same shall
become due and payable either at maturity, upon any redemption, by declaration
of acceleration or otherwise;

                                       30
<PAGE>

               (b) default in the payment of any installment of interest
(including Additional Interest) upon any of the Securities as and when the same
shall become due and payable, and continuance of such default for a period of
five days;

               (c) an event of default, as defined in any instrument of the
Issuer under which there may be issued, or by which there may be secured or
evidenced, any Indebtedness of the Issuer that has resulted in the acceleration
of such Indebtedness, or any default occurring in payment of any such
Indebtedness at final maturity (and after the expiration of any applicable grace
periods), other than such Indebtedness the principal of, and interest on which,
does not, individually, or in the aggregate, exceed $25,000,000; or

               (d) failure on the part of the Issuer to perform or observe any
covenant or agreement contained in Sections 3.8 (Limitations on Liens), 3.9
(Limitations on Subsidiary Indebtedness), 3.10 (Covenant not to Merge,
Consolidate, Sell or Transfer Assets Except Under Certain Conditions), 3.11
(Restricted Payments) or 3.12 (Debt Incurrence Test) herein and such failure
shall continue uncured for more than thirty (30) days after the Issuer has
actual knowledge of such failure; or

               (e) failure on the part of the Issuer to perform or observe any
of its covenants or agreements contained in any other provision of this
Indenture not referred to above and such failure shall continue uncured for more
than thirty (30) days after the Issuer has actual knowledge of such failure;
provided, that if the Issuer commences efforts to cure such default within such
thirty (30)-day period and is diligently attempting to cure such default (and
certifies to the Trustee the steps it is taking), the Issuer may continue to
effect such cure of the default (and such default shall not be deemed an "Event
of Default" hereunder) for an additional sixty (60) days so long as the Issuer
certifies to the Trustee that no other Event of Default has occurred and is
continuing and the Issuer is diligently pursuing such cure; or

               (f) one or more final judgments, decrees or orders of any court,
tribunal, arbitrator, administrative or other governmental body or similar
entity for the payment of money shall be rendered against the Issuer or any of
its properties in an aggregate amount in excess of $25,000,000 (excluding the
amount thereof covered by insurance) and such judgment, decree or order shall
remain unvacated, undischarged and unstayed for more than 60 consecutive days,
except while being contested in good faith by appropriate proceedings; or

               (g) a court having jurisdiction in the premises shall enter a
decree or order for relief in respect of the Issuer or a Subsidiary in an
involuntary case or proceeding under any applicable bankruptcy, insolvency,
reorganization or other similar law now or hereafter in effect, or a decree or
order adjudging the Issuer or a Subsidiary a bankrupt or insolvent, or approving
as properly filed a petition seeking reorganization, arrangement, adjustment, or
composition of or in respect of the Issuer or a Subsidiary under any applicable
federal or state law, or appointing a receiver, liquidator, assignee, custodian,
trustee, sequestrator or similar official of the Issuer or a Subsidiary or for
any substantial part of their respective properties or ordering the winding up
or liquidation of its affairs, shall have been entered, and such decree or order
shall remain unstayed and in effect for a period of 90 consecutive days; or

                                       31
<PAGE>

               (h) the Issuer or a Subsidiary shall commence a voluntary case or
proceeding under any applicable federal or state bankruptcy, insolvency,
reorganization or other similar law now or hereafter in effect or of any other
case or proceeding to be adjudicated a bankrupt or insolvent, or consent to the
entry of a decree or order for relief in an involuntary case or proceeding under
any such law, or to the commencement of any bankruptcy or insolvency case or
proceeding against the Issuer or a Subsidiary, or the filing by the Issuer or a
Subsidiary of a petition or answer or consent seeking reorganization or relief
under any such applicable federal or state law, or the consent by the Issuer or
a Subsidiary to the filing of such petition or to the appointment of or the
taking possession by a custodian, receiver, liquidator, assignee, trustee,
sequestrate or other similar official of the Issuer or a Subsidiary or of any
substantial part of their respective properties, or the making by the Issuer or
a Subsidiary of an assignment for the benefit of creditors, or the taking of
action by the Issuer or a Subsidiary in furtherance of any such action; or

               (i) one or more payments aggregating $25,000,000 or more due to
the Issuer under the terms of the Genco-Marketing Co. PPA (or any successor
long-term agreement between the Issuer and Marketing Co. (or any successor which
is a subsidiary of Ameren Corporation) for the sale of more than 50% of the
capacity and energy of the Issuer's Initial Generating Assets) are not made
within 60 days of the date they are due; or

               (j) the Marketing Co.--CIPS PPA in effect as of the date of this
Indenture is terminated for any reason prior to its scheduled termination date,
unless (A) within 60 days of such termination (or such longer period as may be
needed to secure any required regulatory approvals so long as the parties are
diligently pursuing such approvals), the Marketing Co.-CIPS PPA is replaced with
a power purchase agreement having a term at least equal to the then remaining
term of the Marketing Co.--CIPS PPA between Marketing Co. and a counterparty
with ratings issued by the Rating Agencies at least equal to the lower of (i)
the ratings then assigned to AmerenCIPS' (or its successor's) senior unsecured
debt, or (ii) the ratings then assigned to the Securities, and having similar
economic terms to Marketing Co., or (B) the Issuer provides to the Trustee a
Ratings Reaffirmation of the Rating Agencies' then existing ratings of the
Outstanding Securities; provided, however, no Event of Default shall be deemed
to occur if the Issuer enters into a replacement power purchase agreement
directly with AmerenCIPS (or a successor) for a term at least equal to the
remaining term of the Marketing Co.-CIPS PPA and having similar economic terms
to the Issuer, in which case the Event of Default described in this clause (j)
shall apply on corresponding terms to such replacement power purchase agreement;
or

               (k) at any time that the Marketing Co.-CIPS PPA in effect as of
the date of this Indenture is in effect, the Genco-Marketing Co. PPA in effect
as of the date of this Indenture is terminated for any reason, unless (A) within
60 days of such termination (or such longer period as may be needed to secure
any required regulatory approvals so long as the parties are diligently pursuing
such approvals), the Issuer replaces the Genco-Marketing Co. PPA with a power
purchase agreement with Marketing Co., a successor to Marketing Co. that is a
subsidiary of Ameren Corporation or a non-affiliated power marketing company for
a term at least equal to the remaining term of the Genco-Marketing Co. PPA,
provided that (i) such replacement power purchase agreement has economic terms
to the Issuer similar to the Genco-Marketing Co. PPA, and (ii) any non-
affiliated counterparty under such agreement has ratings assigned to it that
meet

                                       32
<PAGE>

the requirements of clause (j)(A) above, or (B) the Issuer provides to the
Trustee a Ratings Reaffirmation of the Rating Agencies' then existing ratings of
the Outstanding Securities;

then and in each and every such case (other than an Event of Default with
respect to the Issuer specified in Section 4.1(g) or 4.1(h) hereof), unless the
principal of all of the Securities shall have already become due and payable,
either the Trustee or the Holders of not less than 25% in aggregate principal
amount of the Securities then Outstanding hereunder, by notice in writing to the
Issuer (and to the Trustee if given by Holders), may declare the entire
principal of all the Securities and the interest accrued thereon to be due and
payable immediately, and upon any such declaration the same shall become
immediately due and payable. The occurrence of an event described in Section
4.1(g) or 4.1(h) hereof with respect to a Subsidiary shall not constitute an
Event of Default if (x) the creditors of such Subsidiary have no recourse to the
Issuer or (y) such subsidiary is not a "significant subsidiary" as defined in
Regulation S-X under the Securities Act. This provision, however, is subject to
the condition that if, at any time after the principal of the Securities shall
have been so declared due and payable, and before any judgment or decree for the
payment of the moneys due shall have been obtained or entered as hereinafter
provided, the Issuer shall pay or shall deposit with the Trustee a sum
sufficient to pay all matured installments of interest upon all the Securities
and the principal and premium, if any, of any and all Securities that shall have
become due otherwise than by acceleration (with interest upon such principal and
premium, if any, and, to the extent that payment of such interest is enforceable
under applicable law, on overdue installments of interest, at the rate of
interest specified in the Securities, to the date of such payment or deposit)
and such amount as shall be sufficient to cover reasonable compensation to the
Trustee and each predecessor Trustee, their respective agents, attorneys and
counsel, and all other reasonable expenses and liabilities incurred and all
reasonable advances made, by the Trustee and each predecessor Trustee except as
a result of negligence or bad faith, and if any and all Events of Default under
the Indenture, other than the non-payment of the principal that shall have
become due by acceleration, shall have been cured, waived or otherwise remedied
as provided herein, then and in every such case the Holders of a majority in
aggregate principal amount of the Securities then Outstanding, by written notice
to the Issuer and to the Trustee, may waive all defaults (except, unless
theretofore cured, a default in payment of principal of, or premium, if any, or
interest on, the Securities) and rescind and annul such declaration and its
consequences, but no such waiver or rescission and annulment shall extend to or
shall affect any subsequent default or shall impair any right consequent
thereon.

     If an Event of Default specified in Section 4.1(g) or 4.1(h) hereof occurs
with respect to the Issuer, the principal of and accrued interest on the
Securities shall become and be immediately due and payable without any
declaration or other act on the part of the Trustee or any Holder.

     Section 4.2  Collection of Indebtedness by Trustee; Trustee May Prove Debt.
                  -------------------------------------------------------------
The Issuer covenants that (a) in case default shall be made in the payment of
any installment of interest on any of the Securities when such interest shall
have become due and payable, and such default shall have continued for a period
of 10 days or (b) in case default shall be made in the payment of all or any
part of the principal of, or premium, if any, on, any of the Securities when the
same shall have become due and payable, whether upon maturity or upon any
redemption or by declaration of acceleration or otherwise, then upon demand of
the Trustee, the Issuer shall pay

                                       33
<PAGE>

to the Trustee for the benefit of the Holders of the Securities the whole amount
that then shall have become due and payable on all such Securities of principal,
premium or interest, as the case may be (with interest to the date of such
payment upon the overdue principal, premium and, to the extent that payment of
such interest is enforceable under applicable law, on overdue installments of
interest at the rate of interest specified in the Securities); and in addition
thereto, such further amount as shall be sufficient to cover the costs and
expenses of collection, including reasonable compensation to the Trustee and
each predecessor Trustee, their respective agents, attorneys and counsel, and
any reasonable expenses and liabilities incurred, and all reasonable advances
made, by the Trustee and each predecessor Trustee except as a result of its
negligence or bad faith.

     Until such demand is made by the Trustee, the Issuer may pay the principal
of and premium and interest on the Securities to the registered Holders, whether
or not the Securities be overdue.

     In case the Issuer shall fail forthwith to pay such amounts upon such
demand, the Trustee, in its own name and as trustee of an express trust, shall
be entitled and empowered to institute any action or proceedings at law or in
equity for the collection of the sums so due and unpaid, and may prosecute any
such action or proceedings to judgment or final decree, and may enforce any such
judgment or final decree against the Issuer or other obligor upon the Securities
and collect in the manner provided by law out of the property of the Issuer or
other obligor upon the Securities, wherever situated, the moneys adjudged or
decreed to be payable.

     In case there shall be pending proceedings relative to the Issuer or any
other obligor upon the Securities under Title 11 of the United States Code or
any other applicable federal or state bankruptcy, insolvency or other similar
law, or in case a receiver, assignee or trustee in bankruptcy or reorganization,
liquidator, custodian, sequestrator or similar official shall have been
appointed for or taken possession of the Issuer or its property or such other
obligor, or in case of any other comparable judicial proceedings relative to the
Issuer or other obligor upon the Securities, or to the creditors or property of
the Issuer or such other obligor, the Trustee, irrespective of whether the
principal of the Securities shall then be due and payable as therein expressed
or by declaration or otherwise and irrespective of whether the Trustee shall
have made any demand pursuant to the provisions of this Section 4.2, shall be
entitled and empowered, by intervention in such proceedings or otherwise:

               (a) to file and prove a claim or claims for the whole amount of
principal, premium and interest owing and unpaid in respect of the Securities,
and to file such other papers or documents as may be necessary or advisable in
order to have the claims of the Trustee (including any claim for reasonable
compensation to the Trustee and each predecessor Trustee, and their respective
agents, attorneys and counsel, and for reimbursement of all reasonable expenses
and liabilities incurred, and all reasonable advances made, by the Trustee and
each predecessor Trustee, except as a result of negligence or bad faith) and of
the Holders, allowed in any judicial proceedings relative to the Issuer or other
obligor upon the Securities, or to the creditors or property of the Issuer or
such other obligor,

               (b) unless prohibited by applicable law and regulations, to vote
on behalf of the Holders of the Securities in any election of a trustee or a
standby trustee in arrangement,

                                       34
<PAGE>

reorganization, liquidation or other bankruptcy or insolvency proceedings or
person performing similar functions in comparable proceedings, and

               (c) to collect and receive any moneys or other property payable
or deliverable on any such claims, and to distribute all amounts received with
respect to the claims of the Holders and of the Trustee on their behalf; and any
trustee, receiver, or liquidator, custodian or other similar official is hereby
authorized by each of the Holders to make payments to the Trustee, and, in the
event that the Trustee shall consent to the making of payments directly to the
Holders, to pay to the Trustee such amounts as shall be sufficient to cover
reasonable compensation to the Trustee, each predecessor Trustee and their
respective agents, attorneys and counsel, and all other reasonable expenses and
liabilities incurred, and all reasonable advances made, by the Trustee and each
predecessor Trustee except as a result of negligence or bad faith.

     Nothing herein contained shall be deemed to authorize the Trustee to
authorize or consent to or vote for or accept or adopt on behalf of any Holders
any plan of reorganization, arrangement, adjustment or composition affecting the
Securities or the rights of any Holder thereof, or to authorize the Trustee to
vote in respect of the claim of any Holder in any such proceeding except, as
aforesaid, to vote for the election of a trustee in bankruptcy or similar
person.

     All rights of action and of asserting claims under this Indenture, or under
any of the Securities, may be enforced by the Trustee without the possession of
any of the Securities or the production thereof at any trial or other
proceedings relative thereto, and any such action or proceedings instituted by
the Trustee shall be brought in its own name as trustee of an express trust, and
any recovery of judgment, subject to the payment of the expenses, disbursements
and compensation of the Trustee, each predecessor Trustee and their respective
agents and attorneys, shall be for the ratable benefit of the Holders of the
Securities.

     In any proceedings brought by the Trustee (and also any proceedings
involving the interpretation of any provision of this Indenture to which the
Trustee shall be a party) the Trustee shall be held to represent all the Holders
of the Securities, and it shall not be necessary to make any Holders of the
Securities parties to any such proceedings.

     Section 4.3   Application of Proceeds. Any moneys collected by the Trustee
                   -----------------------
pursuant to this Article shall be applied in the following order at the date or
dates fixed by the Trustee and, in case of the distribution of such moneys on
account of principal or interest, upon presentation of the several Securities of
a series and stamping (or otherwise noting) thereon the payment, or issuing
Securities of such series in reduced principal amounts in exchange for the
presented Securities of such series if only partially paid, or upon surrender
thereof if fully paid:

     FIRST: To the payment of costs and expenses, including reasonable
compensation to the Trustee and each predecessor Trustee and their respective
agents and attorneys and of all reasonable expenses and liabilities incurred,
and all reasonable advances made, by the Trustee and each predecessor Trustee
except as a result of negligence or bad faith and all other amounts due under
Section 5.6 hereof;

                                       35
<PAGE>

     SECOND:  In case the principal and premium, if any, of the Securities shall
not have become and be then due and payable, to the payment of interest in
default in the order of the maturity of the installments of such interest, with
interest (to the extent that such interest has been collected by the Trustee)
upon the overdue installments of interest at the rate of interest specified in
the respective Securities of each series, such payments to be made ratably to
the persons entitled thereto, without discrimination or preference;

     THIRD: In case the principal of the Securities shall have become and shall
be then due and payable, to the payment of the whole amount then owing and
unpaid upon all the Securities for principal, premium, and interest, with
interest upon the overdue principal, premium, if any, and (to the extent
permitted by law and to the extent that such interest has been collected by the
Trustee) upon overdue installments of interest at the rate of interest specified
in the respective Securities of each series; and in case such moneys shall be
insufficient to pay in full the whole amount so due and unpaid upon the
Securities of a series, then to the payment of such principal, premium and
interest, without preference or priority of principal, or premium over interest,
or of interest over principal or premium, or of any installment of interest over
any other installment of interest, or of any Security of such series over any
other Security of such series, ratably to the aggregate of such principal and
accrued and unpaid interest; and

     FOURTH:  To the payment of the remainder, if any, to the Issuer or any
other Person lawfully entitled thereto.

     The Trustee may fix a record date and payment date for any payment to
Holders pursuant to this Section 4.3.

     Section 4.4  Suits for Enforcement. In case an Event of Default has
                  ---------------------
occurred, has not been waived and is continuing, the Trustee may in its
discretion proceed to protect and enforce the rights vested in it by this
Indenture by such appropriate judicial proceedings as the Trustee shall deem
most effectual to protect and enforce any of such rights, either at law or in
equity or in bankruptcy or otherwise, whether for the specific enforcement of
any covenant or agreement contained in this Indenture or in aid of the exercise
of any power granted in this Indenture or to enforce any other legal or
equitable right vested in the Trustee by this Indenture or by law.

     Section 4.5  Restoration of Rights on Abandonment of Proceedings. In case
                  ---------------------------------------------------
the Trustee shall have proceeded to enforce any right under this Indenture and
such proceedings shall have been discontinued or abandoned for any reason, or
shall have been determined adversely to the Trustee, then and in every such case
the Issuer and the Trustee shall be restored respectively to their former
positions and rights hereunder, and all rights, remedies and powers of the
Issuer, the Trustee and the Holders shall continue as though no such proceedings
had been taken.

     Section 4.6  Limitations of Suits by Holders. No Holder of any Security
                  -------------------------------
shall have any right by virtue or by availing of any provision of this Indenture
to institute any action or proceeding at law or in equity or in bankruptcy or
otherwise upon or under or with respect to this Indenture, or for the
appointment of a trustee, receiver, liquidator, custodian or other similar
official or for any other remedy hereunder, unless such Holder previously shall
have given to the Trustee written notice of default and of the continuance
thereof, as hereinbefore provided, and

                                       36
<PAGE>

unless also the Holders of not less than 25% in aggregate principal amount of
the Securities then Outstanding shall have made written request upon the Trustee
to institute such action or proceedings in its own name as trustee hereunder and
shall have offered to the Trustee such reasonable indemnity as it may require
against the costs, expenses and liabilities to be incurred therein or thereby
and the Trustee for 30 days after its receipt of such notice, request and offer
of indemnity shall have failed to institute any such action or proceedings and
no direction inconsistent with such written request shall have been given to the
Trustee pursuant to Section 4.8 hereof; it being understood and intended, and
being expressly covenanted by the taker and Holder of every Security with every
other taker and Holder and the Trustee, that no one or more Holders of
Securities shall have any right in any manner whatever by virtue or by availing
of any provision of this Indenture to affect, disturb or prejudice the rights of
any other Holder of Securities, or to obtain or seek to obtain priority over or
preference to any other such Holder or to enforce any right under this
Indenture, except in the manner herein provided and for the equal, ratable and
common benefit of all Holders of Securities. For the protection and enforcement
of the provisions of this Section 4.6 each and every Holder and the Trustee
shall be entitled to such relief as can be given either at law or in equity.

     Section 4.7  Powers and Remedies Cumulative; Delay or Omission Not Waiver
                  ------------------------------------------------------------
of Default.  Except as provided in Section 2.7 hereof, no right or remedy herein
----------
conferred upon or reserved to the Trustee or to the Holders is intended to be
exclusive of any other right or remedy, and every right and remedy shall, to the
extent permitted by law, be cumulative and in addition to every other right and
remedy given hereunder or now or hereafter existing at law or in equity or
otherwise. The assertion or employment of any right or remedy hereunder, or
otherwise, shall not prevent the concurrent assertion or employment of any other
appropriate right or remedy.

     No delay or omission of the Trustee or of any Holder of any of the
Securities to exercise as aforesaid any such right or power accruing upon any
Event of Default occurring and continuing as aforesaid shall impair any such
right or power or shall be construed to be a waiver of any such Event of Default
or an acquiescence therein; and, subject to Section 4.6 hereof, every power and
remedy given by this Indenture or by law to the Trustee or to the Holders may be
exercised from time to time, and as often as shall be deemed expedient, by the
Trustee or by the Holders.

     Section 4.8  Control by Holders.  The Holders of a majority in aggregate
                  ------------------
principal amount of the Securities at the time Outstanding shall have the right
to direct the time, method and place of conducting any proceeding for any remedy
available to the Trustee, or exercising any trust or power conferred on the
Trustee by this Indenture; provided that such direction shall not be otherwise
                           --------
than in accordance with law and the provisions of this Indenture; and provided
                                                                      --------
further that (subject to the provisions of Section 5.1 hereof) the Trustee shall
-------
have the right to decline to follow any such direction if the Trustee, being
advised by counsel, shall determine that the action or proceeding so directed
may not lawfully be taken or if the Trustee in good faith by its board of
directors, the executive committee, or a trust committee of directors or
Responsible Officers of the Trustee shall determine that the action or
proceedings so directed would involve the Trustee in personal liability or if
the Trustee in good faith shall so determine that the actions or forbearances
specified in or pursuant to such direction shall be unduly prejudicial to the
interests of Holders of the Securities not joining in the giving of said
direction, it being understood that (subject to Section 5.1 hereof) the Trustee
shall have no duty to ascertain

                                       37
<PAGE>

whether or not such actions or forbearances are unduly prejudicial to such
Holders. Nothing in this Indenture shall impair the right of the Trustee in its
discretion to take any action deemed proper by the Trustee and which is not
inconsistent with such direction by Holders.

     Section 4.9  Waiver of Past Defaults.  Prior to the declaration of the
                  -----------------------
maturity of the Securities as provided in Section 4.1 hereof, the Holders of a
majority in aggregate principal amount of the Securities at the time Outstanding
may on behalf of the Holders of all the Securities waive any past default or
Event of Default hereunder and its consequences, except a default (a) in the
payment of principal of, premium, if any, or interest on any of the Securities
or (b) in respect of a covenant or provision hereof that cannot be modified or
amended without the consent of the Holder of each Security affected. If a
default shall occur hereunder by reason of the Issuer's failure to comply with
Section 3.9 hereof and the Issuer shall cease to be in breach of such Section
prior to the time that such default constitutes an Event of Default, such
default and its consequences shall be deemed waived by the Holders without any
further action required on the part of the Trustee or the Holders. In the case
of any such waiver, the Issuer, the Trustee and the Holders of the Securities
shall be restored to their former positions and rights hereunder, respectively;
but no such waiver shall extend to any subsequent or other default or impair any
right consequent thereon.

     Upon any such waiver, such default shall cease to exist and be deemed to
have been cured and not to have occurred, and any Event of Default arising
therefrom shall be deemed to have been cured, and not to have occurred for every
purpose of this Indenture; but no such waiver shall extend to any subsequent or
other default or Event of Default or impair any right consequent thereon.

     Section 4.10  Rights of Holders to Receive Payment.  Notwithstanding any
                   ------------------------------------
other provision of this Indenture (including, without limitation, Section 4.6
hereof), the right of any Holder to receive, and to institute suit to enforce,
payment of the principal of, and premium, if any, and interest on the Securities
on or after the respective due dates expressed in such Securities (including
upon redemption and acceleration of the maturity of the principal of and
premium, if any, and interest on the Securities), shall not be affected or
impaired, and shall be absolute and unconditional.

     Section 4.11  Notice of Default.  Within 90 calendar days after the
                   -----------------
occurrence of any Event of Default hereunder known to a Responsible Officer of
the Trustee with respect to the Securities, the Trustee shall transmit by mail
to all Holders, as their names and addresses appear in the Securities Register,
notice of such Event of Default, unless such Event of Default shall have been
cured or waived; provided that, except in the case of an Event of Default in the
payment of the principal of or premium, if any, or interest on any Security or
in the payment of any sinking or purchase fund installment, the Trustee shall be
protected in withholding such notice if and so long as it in good faith
determines that the withholding of such notice is in the interests of the
Holders.

                                   ARTICLE V

                            CONCERNING THE TRUSTEE
                            ----------------------

                                       38
<PAGE>

     Section 5.1  Duties and Responsibilities of the Trustee; During Default;
                  -----------------------------------------------------------
Prior to Default. The Trustee, prior to the occurrence of an Event of Default
----------------
and after the curing or waiving of all Events of Default that may have occurred,
undertakes to perform only such duties as are specifically set forth in this
Indenture. In case an Event of Default has occurred (which has not been cured or
waived) the Trustee shall exercise such of the rights and powers vested in it by
this Indenture, and use the same degree of care and skill in their exercise, as
a prudent man would exercise or use under the circumstances in the conduct of
his own affairs. No provision of this Indenture shall be construed to relieve
the Trustee from liability for its own grossly negligent action, its own grossly
negligent failure to act or its own willful misconduct, except that

               (a)  prior to the occurrence of an Event of Default and after the
curing or waiving of all such Events of Default that may have occurred:

                    (i)    the duties and obligations of the Trustee shall be
          determined solely by the express provisions of this Indenture, and the
          Trustee shall not be liable except for the performance of such duties
          and obligations as are specifically set forth in this Indenture, and
          no implied covenants or obligations shall be read into this Indenture
          against the Trustee; and

                    (ii)   in the absence of bad faith on the part of the
          Trustee, the Trustee may conclusively rely, as to the truth of the
          statements and the correctness of the opinions expressed therein, upon
          any statements, certificates or opinions furnished to the Trustee and
          conforming to the requirements of this Indenture; but in the case of
          any such statements, certificates or opinions which by any provision
          hereof are specifically required to be furnished to the Trustee, the
          Trustee shall be under a duty to examine the same to determine whether
          or not they conform to the requirements of this Indenture;

               (b)  the Trustee shall not be liable for any error of judgment
made in good faith by a Responsible Officer or Responsible Officers of the
Trustee, unless it shall be proved that the Trustee was grossly negligent in
ascertaining the pertinent facts; and

               (c)  the Trustee shall not be liable with respect to any action
taken or omitted to be taken by it in good faith in accordance with the
direction of the Holders of not less than a majority in principal amount of the
Securities at the time Outstanding relating to the time, method and place of
conducting any proceeding for any remedy available to the Trustee, or exercising
any trust or power conferred upon the Trustee, under this Indenture.

     None of the provisions contained in this Indenture shall require the
Trustee to expend or risk its own funds or otherwise incur personal financial
liability in the performance of any of its duties or in the exercise of any of
its rights or powers, if there shall be reasonable ground for believing that the
repayment of such funds or adequate indemnity against such liability is not
reasonably assured to it.

     Section 5.2  Certain Rights of the Trustee.  Subject to Section 5.1 hereof:
                  -----------------------------

               (a)  the Trustee may rely and shall be protected in acting or
refraining from acting upon any resolution, Officers' Certificate or any other
certificate (including, without limitation, any certificate provided to the
Trustee pursuant to Section 3.7 hereof), statement,

                                       39
<PAGE>

instrument, opinion, report, notice, request, consent, order, bond, debenture,
note, coupon, security or other paper or document believed by it to be genuine
and to have been signed or presented by the proper party or parties;

          (b)  any request, direction, order or demand of the Issuer mentioned
herein shall be sufficiently evidenced by an Officers' Certificate (unless other
evidence in respect thereof be herein specifically prescribed) and any
resolution of the Board of Directors may be evidenced to the Trustee by a copy
thereof certified by the Secretary or an Assistant Secretary of the Issuer;

          (c)  the Trustee may consult with counsel and any advice or Opinion of
Counsel shall be full and complete authorization and protection in respect of
any action taken, suffered or omitted to be taken by it hereunder in good faith
and in accordance with such advice or Opinion of Counsel;

          (d)  the Trustee shall be under no obligation to exercise any of the
trusts or powers vested in it by this Indenture at the request, order or
direction of any of the Holders pursuant to the provisions of this Indenture,
unless such Holders shall have offered to the Trustee reasonable security or
indemnity against the costs, expenses and liabilities that might be incurred
therein or thereby;

          (e)  the Trustee shall not be liable for any action taken or omitted
by it in good faith and believed by it to be authorized or within the
discretion, rights or powers conferred upon it by this Indenture;

          (f)  the Trustee shall not be bound to make any investigation into the
facts or matters stated in any resolution, certificate, statement, instrument,
opinion, report, notice, request, consent, order, approval, appraisal, bond,
debenture, note, coupon, security, or other paper or document unless requested
in writing so to do by the Holders of not less than a majority in aggregate
principal amount of the Securities then Outstanding; provided that, if the
                                                     --------
payment within a reasonable time to the Trustee of the costs, expenses or
liabilities likely to be incurred by it in the making of such investigation is,
in the opinion of the Trustee, not reasonably assured by the security afforded
to it by the terms of this Indenture, the Trustee may require reasonable
indemnity against such expenses or liabilities as a condition to proceeding; the
reasonable expenses of every such examination shall be paid by the Issuer, or by
the Trustee or any predecessor Trustee and repaid by the Issuer upon demand; and

          (g)  the Trustee shall not be bound to make any investigation into the
facts or matters stated in any resolution, certificate, statement, instrument,
opinion, report, notice, request, direction, consent, order, bond, debenture,
note, other evidence of indebtedness or other paper or document, but the
Trustee, in its discretion, may make such further inquiry or investigation into
such facts or matters as it may see fit, and, if the Trustee shall determine to
make such further inquiry or investigation, it shall be entitled to examine the
books, records and premises of the Issuer, personally or by agent or attorney.

     Section 5.3  Trustee Not Responsible for Recitals, Disposition of
                  ----------------------------------------------------
Securities or Application of Proceeds Thereof. The recitals contained herein and
---------------------------------------------
in the Securities, except the

                                       40
<PAGE>

Trustee's certificates of authentication, shall be taken as the statements of
the Issuer, and the Trustee assumes no responsibility for the correctness of the
same. The Trustee makes no representation as to the validity or sufficiency of
this Indenture or of the Securities. The Trustee shall not be accountable for
the use or application by the Issuer of any of the Securities or of the proceeds
thereof.

     Section 5.4  Trustee and Agents May Hold Securities; Collections, etc.  The
                  --------------------------------------------------------
Trustee or any agent of the Issuer or the Trustee, in its individual or any
other capacity, may become the owner or pledgee of Securities with the same
rights it would have if it were not the Trustee or such agent and may otherwise
deal with the Issuer and receive, collect, hold and retain collections from the
Issuer with the same rights it would have if it were not the Trustee or such
agent.

     Section 5.5  Moneys Held by Trustee.  Subject to the provisions of Section
                  -----------------------
9.4 hereof, all moneys received by the Trustee shall, until used or applied as
herein provided, be held in trust for the purposes for which they were received,
but need not be segregated from other funds except to the extent required by
mandatory provisions of law. Neither the Trustee nor any agent of the Issuer or
the Trustee shall be under any liability for interest on any moneys received by
it hereunder, except as the Issuer and the Trustee otherwise may agree.

     Section 5.6  Compensation and Indemnification of Trustee and its Prior
                  ---------------------------------------------------------
Claim. The Issuer covenants and agrees to pay to the Trustee from time to time
-----
as shall be agreed upon between the Issuer and the Trustee in writing from time
to time, and the Trustee shall be entitled to, reasonable compensation (which
shall not be limited by any provision of law relating to the compensation of a
trustee of an express trust), and the Issuer covenants and agrees to pay or
reimburse the Trustee and each predecessor Trustee upon its request for all
reasonable expenses, disbursements and advances incurred or made by or on behalf
of it in accordance with any of the provisions of this Indenture (including the
reasonable compensation and expenses and disbursements of its counsel and of all
agents and other persons not regularly in its employ), except to the extent any
such expense, disbursement or advance may arise from the Trustee's negligence or
bad faith. The Issuer also covenants to indemnify the Trustee and each
predecessor Trustee for, and to hold it harmless against, any and all loss,
liability, damage, claims or expense arising out of or in connection with the
acceptance or administration of this Indenture or the trusts hereunder and its
duties hereunder and the performance of its duties hereunder, including the
costs and expenses of defending and investigating any claim of liability in the
premises, except to the extent any such loss, liability or expense is due to its
own negligence or bad faith. The obligations of the Issuer under this Section
5.6 to compensate and indemnify the Trustee and each predecessor Trustee and to
pay or reimburse the Trustee and each predecessor Trustee for expenses,
disbursements and advances shall constitute additional indebtedness hereunder
and shall survive the satisfaction and discharge of this Indenture.

     Section 5.7  Right of Trustee to Rely on Officers' Certificate, etc.
                  ------------------------------------------------------
Subject to Section 5.1 and Section 5.2 hereof, whenever in the administration of
the trusts of this Indenture the Trustee shall deem it necessary or desirable
that a matter be proved or established prior to taking or suffering or omitting
any action hereunder, such matter (unless other evidence in respect thereof be
herein specifically prescribed) may, in the absence of negligence or bad faith
on the

                                       41
<PAGE>

part of the Trustee, be deemed to be conclusively proved and established by an
Officers' Certificate delivered to the Trustee.

     Section 5.8  Persons Eligible for Appointment as Trustee.  The Trustee
                  -------------------------------------------
hereunder shall at all times be a corporation organized and doing business under
the laws of the United States or of a state thereof, having a combined capital
and surplus of at least $500,000,000, and which is authorized under such laws to
exercise corporate trust powers and subject to supervision or examination by
federal or state authority. If such corporation publishes reports of condition
at least annually, pursuant to law or to the requirements of a federal, state or
District of Columbia supervising or examining authority, then for the purposes
of this Section 5.8, the combined capital and surplus of such corporation shall
be deemed to be its combined capital and surplus as set forth in its most recent
report of condition so published. No obligor on the Securities or Person
directly or indirectly controlling, controlled by or under common control with
such obligor shall serve as Trustee.

     Section 5.9  Resignation and Removal; Appointment of Successor Trustee. (a)
                  ---------------------------------------------------------
The Trustee may at any time resign by giving written notice of resignation to
the Issuer and by mailing notice thereof by first-class mail to Holders of
Securities at their last addresses as they shall appear on the Securities
Register. Upon receiving such notice of resignation, the Issuer shall promptly
appoint a successor trustee by written instrument in duplicate, executed by
authority of the Board of Directors, one copy of which instrument shall be
delivered to the resigning Trustee and one copy to the successor trustee. If no
successor trustee shall have been so appointed and have accepted appointment
within 30 days after the mailing of such notice of resignation, the resigning
Trustee may petition any court of competent jurisdiction for the appointment of
a successor trustee, or any Holder who has been a bona fide Holder of a Security
or Securities for at least six months may, on behalf of himself and all others
similarly situated, petition any such court for the appointment of a successor
trustee. Such court may thereupon, after such notice, if any, as it may deem
proper and prescribe, appoint a successor trustee.

          (b)  In case at any time any of the following shall occur:

               (i)    the Trustee shall fail to comply with the provisions of
          Section 310(b) of the Trust Indenture Act, after written request
          therefor by the Issuer or by any Holder who has been a bona fide
          Holder of a Security or Securities for at least six months;

               (ii)   the Trustee shall cease to be eligible in accordance with
          the provisions of Section 5.8 hereof and shall fail to resign after
          written request therefor by the Issuer or by any such Holder; or

               (iii)  the Trustee shall become incapable of acting, or shall be
          adjudged a bankrupt or insolvent, or a receiver or liquidator of the
          Trustee or of its property shall be appointed, or any public officer
          shall take charge or control of the Trustee or of its property or
          affairs for the purpose of rehabilitation, conservation or
          liquidation;

then, in any such case, the Issuer may remove the Trustee and appoint a
successor trustee by written instrument, in duplicate, executed by order of the
Board of Directors of the Issuer, one

                                       42
<PAGE>

copy of which instrument shall be delivered to the Trustee so removed and one
copy of which shall be delivered to the successor trustee, or, any Holder who
has been a bona fide Holder of a Security or Securities for at least six months
may on behalf of himself and all others similarly situated, petition any court
of competent jurisdiction for the removal of the Trustee and the appointment of
a successor trustee. Such court may thereupon, after such notice, if any, as it
may deem proper and prescribe, remove the Trustee and appoint a successor
trustee.

          (c)  The Holders of a majority in aggregate principal amount of the
Securities at the time Outstanding may at any time remove the Trustee and
appoint a successor trustee by delivering to the Trustee so removed, to the
successor trustee so appointed and to the Issuer the evidence provided for in
Section 6.1 hereof of the action in that regard taken by the Holders.

          (d)  Any resignation or removal of the Trustee and any appointment of
a successor trustee pursuant to any of the provisions of this Section 5.9 shall
become effective only upon acceptance of appointment by the successor trustee as
provided in Section 5.10 hereof.

     Section 5.10  Acceptance of Appointment by Successor Trustee.  Any
                   ----------------------------------------------
successor trustee appointed as provided in Section 5.9 hereof shall execute and
deliver to the Issuer and to its predecessor Trustee an instrument accepting
such appointment hereunder, and thereupon the resignation or removal of the
predecessor Trustee shall become effective and such successor trustee, without
any further act, deed or conveyance, shall become vested with all rights,
powers, duties and obligations of its predecessor hereunder, with like effect as
if originally named as trustee herein; but, nevertheless, on the written request
of the Issuer or of the successor trustee, upon payment of its charges then
unpaid, the Trustee ceasing to act shall, subject to Section 9.4 hereof, pay
over to the successor trustee all moneys at the time held by it hereunder and
shall execute and deliver an instrument transferring to such successor trustee
all such rights, powers, duties and obligations. Upon request of any such
successor trustee, the Issuer shall execute appropriate instruments in writing
for more fully and certainly vesting in and confirming to such successor such
rights and powers. Any Trustee ceasing to act shall, nevertheless, retain a
prior claim upon all property or funds held or collected by such Trustee to
secure any amounts then due it pursuant to the provisions of Section 5.6 hereof.

     Upon acceptance of appointment by a successor trustee as provided in this
Section 5.10, the Issuer shall mail notice thereof by first-class mail to the
Holders of Securities at their last addresses as they shall appear in the
Securities Register. If the acceptance of appointment is substantially
contemporaneous with the resignation then the notice called for by the preceding
sentence may be combined with the notice called for by Section 5.9 hereof. If
the Issuer fails to mail such notice within 10 days after acceptance of
appointment by the successor trustee, the successor trustee shall cause such
notice to be mailed at the expense of the Issuer.

     Notwithstanding replacement of the Trustee pursuant to this Section 5.10,
the Issuer's obligations under Section 5.6 hereof shall continue for the benefit
of the retiring Trustee.

     Section 5.11  Merger, Conversion, Consolidation or Succession to Business
                   -----------------------------------------------------------
of Trustee. Any corporation into which the Trustee may be merged or converted or
----------
with which it may be consolidated, or any corporation resulting from any merger,
conversion or consolidation to which the Trustee shall be a party, or any
corporation succeeding to the corporate trust business of the

                                       43
<PAGE>

Trustee, shall be the successor of the Trustee hereunder, provided that such
corporation shall be eligible under the provisions of Section 5.8 hereof,
without the execution or filing of any paper or any further act on the part of
any of the parties hereto, anything herein to the contrary notwithstanding.

     In case at the time such successor to the Trustee shall succeed to the
trusts created by this Indenture any of the Securities shall have been
authenticated but not delivered, any such successor to the Trustee may adopt the
certificate of authentication of any predecessor Trustee and deliver such
Securities so authenticated; and, in case at that time any of the Securities
shall not have been authenticated, any successor to the Trustee may authenticate
such Securities either in the name of any predecessor hereunder or in the name
of the successor trustee, and in such cases such certificate shall have the full
force which it is anywhere in the Securities or in this Indenture provided that
the certificate of the Trustee shall have; provided, that the right to adopt the
certificate of authentication of any predecessor Trustee or to authenticate
Securities in the name of any predecessor Trustee shall apply only to its
successor or successors by merger, conversion or consolidation.

     Section 5.12  Preferential Collection of Claims Against Issuer. The Trustee
                   ------------------------------------------------
shall be subject to, and shall comply with, the provisions of Section 311 of the
Trust Indenture Act.

                                  ARTICLE VI

                            CONCERNING THE HOLDERS
                            ----------------------

     Section 6.1  Evidence of Action Taken by Holders.  Any request, demand,
                  -----------------------------------
authorization, direction, notice, consent, waiver or other action provided by
this Indenture to be given or taken by Holders may be embodied in and evidenced
by one or more instruments of substantially similar tenor signed by such
Holders, in person or by agent duly appointed in writing; and, except as herein
otherwise expressly provided, such action shall become effective when such
instrument or instruments are delivered to the Trustee. Proof of execution of
any instrument or of a writing appointing any such agent shall be sufficient for
any purpose of this Indenture and (subject to Section 5.1 and Section 5.2
hereof) conclusive in favor of the Trustee and the Issuer, if made in the manner
provided in this Article.

     Section 6.2  Proof of Execution of Instruments and of Holding of Securities
                  --------------------------------------------------------------
Record Date.  Subject to Section 5.1 and Section 5.2 hereof, the execution of
-----------
any instrument by a Holder or his agent or proxy may be provided in accordance
with such reasonable rules and regulations as may be prescribed by the Trustee
or in such manner as shall be satisfactory to the Trustee. The holding of
Securities shall be proved by the Securities Register or by a certificate of the
Security Registrar thereof. The Issuer may set a record date for purposes of
determining the identity of Holders of Securities entitled to vote or consent to
any action referred to in Section 6.1 hereof, which record date may be set at
any time or from time to time by notice to the Trustee, for any date or dates
(in the case of any adjournment or resolicitation) not more than 60 days nor
less than five days prior to the proposed date of such vote or consent, and
thereafter, notwithstanding any other provisions hereof, only Holders of
Securities of record on such record date shall be entitled to so vote or give
such consent or to withdraw such vote or consent.

                                       44
<PAGE>

     Section 6.3  Holders to Be Treated as Owners.  The Issuer, the Trustee and
                  -------------------------------
any agent of the Issuer or the Trustee may deem and treat the Person in whose
name any Security shall be registered upon the Securities Register as the
absolute owner of such Security (whether or not such Security shall be overdue
and notwithstanding any notation of ownership or other writing thereon) for the
purpose of receiving payment of or on account of the principal of, and premium,
if any, on and, subject to the provisions of this Indenture, interest on such
Security and for all other purposes; and neither the Issuer nor the Trustee nor
any agent of the Issuer or the Trustee shall be affected by any notice to the
contrary. All such payments so made to any such Person, or upon his order, shall
be valid and, to the extent of the sum or sums so paid, effectual to satisfy and
discharge the liability for moneys payable upon any such Security.

     Section 6.4  Securities Owned by Issuer Deemed Not Outstanding.  In
                  -------------------------------------------------
determining whether the Holders of the requisite aggregate principal amount of
Securities have concurred in any direction, consent or waiver under this
Indenture, Securities that are owned by the Issuer or any other obligor on the
Securities or by any Person directly or indirectly controlling or controlled by
or under direct or indirect common control with the obligor on the Securities
shall be disregarded and deemed not to be Outstanding for the purpose of any
such determination, except that for the purpose of determining whether the
Trustee shall be protected in relying on any such direction, consent or waiver
only Securities that the Trustee knows are so owned shall be so disregarded.
Securities so owned that have been pledged in good faith may be regarded as
Outstanding if the pledgee establishes to the satisfaction of the Trustee the
pledgee's right so to act with respect to such Securities and that the pledgee
is not the Issuer or any other obligor upon the Securities or any Person
directly or indirectly controlling or controlled by or under direct or indirect
common control with the Issuer or any other obligor on the Securities. In case
of a dispute as to such right, the advice of counsel shall be full protection in
respect of any decision made by the Trustee in accordance with such advice. Upon
request of the Trustee, the Issuer shall furnish to the Trustee promptly an
Officers' Certificate listing and identifying all Securities, if any, known by
the Issuer to be owned or held by or for the account of any of the above-
described Persons; and, subject to Section 5.1 and Section 5.2 hereof, the
Trustee shall be entitled to accept such Officers' Certificate as conclusive
evidence of the facts therein set forth and of the fact that all Securities not
listed therein are Outstanding for the purpose of any such determination.

     Section 6.5  Right of Revocation of Action Taken.  At any time prior to
                  -----------------------------------
(but not after) the evidencing to the Trustee, as provided in Section 6.1
hereof, of the taking of any action by the Holders of the percentage in
aggregate principal amount of the Securities specified in this Indenture in
connection with such action, any Holder of a Security the serial number of which
is shown by the evidence to be included among the serial numbers of the
Securities the Holders of which have consented to such action may, by filing
written notice at the Corporate Trust Office and upon proof of holding as
provided in this Article, revoke such action so far as concerns such Security.
Except as aforesaid any such action taken by the Holder of any Security shall be
conclusive and binding upon such Holder and upon all future Holders and owners
of such Security and of any Securities issued in exchange or substitution
therefor, irrespective of whether or not any notation in regard thereto is made
upon any such Security. Any action taken by the Holders of the percentage in
aggregate principal amount of the Securities specified in this Indenture in
connection with such action shall be conclusively binding upon the Issuer, the
Trustee and the Holders of all such Securities.

                                       45
<PAGE>

                                  ARTICLE VII

                            SUPPLEMENTAL INDENTURES
                            -----------------------

     Section 7.1  Supplemental Indentures Without Consent of Holders.  The
                  --------------------------------------------------
Issuer, when authorized by a resolution of its Board of Directors, and the
Trustee may from time to time and at any time enter into an indenture or
indentures supplemental hereto for one or more of the following purposes:

          (a)  to convey, transfer, assign, mortgage or pledge to the Trustee as
security for the Securities any property or assets;

          (b)  to establish the form and terms of Securities of any series
permitted by this Indenture, including without limitation the Exchange Notes;

          (c)  to evidence the succession of another corporation to the Issuer,
or successive successions, and the assumption by the successor corporation of
the covenants, agreements and obligations of the Issuer pursuant to Article
Eight hereof;

          (d)  to add to the covenants of the Issuer such further covenants,
restrictions, conditions or provisions as its Board of Directors shall consider
to be for the protection of the Holders of some or all of the Securities or for
the maintenance of ratings on some or all of the Securities, and to make the
occurrence, or the occurrence and continuance of a default in any such
additional covenants, restrictions, conditions or provisions an Event of Default
permitting the enforcement of all or any of the several remedies provided in
this Indenture as herein set forth; provided, that in respect of any such
                                    --------
additional covenant, restriction, condition or provision such supplemental
indenture may provide for a particular period of grace after default (which
period may be shorter or longer than that allowed in the case of other defaults)
or may provide for immediate enforcement upon such an Event of Default or may
limit the remedies available to the Trustee upon such an Event of Default or may
limit the right of the Holders of a majority in aggregate principal amount of
the Securities to waive such an Event of Default;

          (e)  to change or eliminate any of the provisions of this Indenture;
provided that any such change or elimination shall become effective only when
there is no Security Outstanding created prior to the execution of such Series
Supplemental Indenture which is entitled to the benefit of such provision or
such change or elimination is applicable only to Securities issued after the
effective date of such change or elimination;

          (f)  to add to or modify any transfer restrictions or securities
legends as set forth herein;

          (g)  to cure any ambiguity or to cure, correct or supplement any
defective provision contained herein or in the Securities of a series, or to
make such other provisions in regard to matters or questions arising under this
Indenture or under any supplemental indenture as the Board of Directors may deem
necessary or desirable, and in any case which the Trustee and the Issuer shall
determine (i) are not inconsistent with this Indenture and the Securities of
such series and (ii) shall not adversely affect the interests of the Holders of
the Securities of such series; and

                                       46
<PAGE>

          (h)  to modify or supplement this Indenture or any indenture
supplemental hereto in such manner as to permit the qualification thereof under
the Trust Indenture Act or any other similar federal statute hereafter in
effect.

     The Trustee is hereby authorized to join in the execution of any such
supplemental indenture, to make any further appropriate agreements and
stipulations that may be therein contained and to accept the conveyance,
transfer, assignment, mortgage or pledge of any property thereunder, but the
Trustee shall not be obligated to enter into any such supplemental indenture
that affects the Trustee's own rights, duties or immunities under this Indenture
or otherwise.

     Any supplemental indenture authorized by the provisions of this Section 7.1
may be executed without the consent of the Holders of any of the Securities at
the time Outstanding, notwithstanding any of the provisions of Section 7.2
hereof.

     Section 7.2  Supplemental Indentures with Consent of Holders.  With the
                  -----------------------------------------------
consent (evidenced as provided in Article VI hereof) of the Holders of not less
than a majority in aggregate principal amount of the Securities of all series at
the time Outstanding considered as one class, the Issuer, when authorized by a
resolution of its Board of Directors, and the Trustee may, from time to time and
at any time, modify this Indenture or any indentures supplemental hereto or the
rights of the Holders of the Securities; provided, that if there shall be
                                         --------
Securities of more than one series Outstanding hereunder and if a proposed
supplemental indenture shall directly affect the rights of the Holders of one or
more, but less than all, of such series, then the consent only of the Holders of
not less than a majority in aggregate principal amount of the Outstanding
Securities of all series so directly affected, considered as one class, shall be
required; provided, further, that at any time when Exchange Notes, Series A
          --------  -------
Notes and Series B Notes are all outstanding, such Exchange Notes shall not be
deemed to constitute a separate series for purposes of this section but shall be
included in the series to which the notes that were exchanged for such Exchange
Notes belonged; provided further, that no such supplemental indenture shall (a)
                -------- -------
change the Stated Maturity of the principal of, or any installment of principal
of or interest on, any Security, or reduce the principal amount thereof, or
reduce the rate or extend the time of payment of interest thereon, or reduce any
amount payable on redemption thereof or impair or affect the right of any Holder
to institute suit for the payment thereof, in each case without the consent of
the Holder of each Security so affected, or (b) without the consent of the
Holders of all Securities then Outstanding, (i) reduce the aforesaid percentage
of Securities, the consent of the Holders of which is required for any such
modification, or the percentage of Securities, the consent of the Holders of
which is required for any waiver provided for in this Indenture, (ii) change any
obligation of the Issuer to maintain an office or agency in the places and for
the purposes specified in Section 3.2 or (iii) make any change in Section 4.9 or
this Section 7.2, except to increase any percentage or to provide that certain
other provisions of this Indenture cannot be modified or waived without the
consent of the Holders of each Outstanding Security affected thereby.

     Upon the request of the Issuer, accompanied by a copy of a resolution of
the Board of Directors certified by the Secretary or an Assistant Secretary of
the Issuer authorizing the execution of any such supplemental indenture, and
upon the filing with the Trustee of evidence of the consent of Holders and other
documents, if any, required by Section 6.1 hereof the Trustee

                                       47
<PAGE>

shall join with the Issuer in the execution of such supplemental indenture
unless such supplemental indenture affects the Trustee's own rights, duties or
immunities under this Indenture or otherwise, in which case the Trustee may in
its discretion, but shall not be obligated to, enter into such supplemental
indenture.

     It shall not be necessary for the consent of the Holders under this Section
7.2 to approve the particular form of any proposed supplemental indenture, but
it shall be sufficient if such consent shall approve the substance thereof.

     Promptly after the execution by the Issuer and the Trustee of any
supplemental indenture pursuant to the provisions of this Section 7.2, the
Issuer shall mail a notice thereof by first-class mail to the Holders of
Securities at their addresses as they shall appear on the Securities Register,
setting forth in general terms the substance of such supplemental indenture. Any
failure of the Issuer to mail such notice, or any defect therein, shall not,
however, in any way impair or affect the validity of any such supplemental
indenture.

     Section 7.3  Effect of Supplemental Indenture. Upon the execution of any
                  --------------------------------
supplemental indenture pursuant to the provisions hereof, this Indenture shall
be and be deemed to be modified and amended in accordance therewith and the
respective rights, limitations of rights, obligations, duties and immunities
under this Indenture of the Trustee, the Issuer and the Holders of Securities
shall thereafter be determined, exercised and enforced hereunder subject in all
respects to such modifications and amendments, and all the terms and conditions
of any such supplemental indenture shall be and be deemed to be part of the
terms and conditions of this Indenture for any and all purposes.

     Section 7.4  Documents to Be Given to Trustee. The Trustee, subject to the
                  --------------------------------
provisions of Section 5.1 and Section 5.2 hereof, may receive an Officers'
Certificate and an Opinion of Counsel as conclusive evidence that any such
supplemental indenture complies with the applicable provisions of this
Indenture.

     Section 7.5  Notation of Securities in Respect of Supplemental Indentures.
                  ------------------------------------------------------------
Securities authenticated and delivered after the execution of any supplemental
indenture pursuant to the provisions of this Article Seven may bear a notation
in form approved by the Trustee as to any matter provided for by such
supplemental indenture or as to any action taken at any such meeting. If the
Issuer or the Trustee shall so determine, new Securities so modified as to
conform, in the opinion of the Trustee and the Board of Directors, to any
modification of this Indenture contained in any such supplemental indenture may
be prepared by the Issuer, authenticated by the Trustee and delivered in
exchange for the Securities then Outstanding.

                                 ARTICLE VIII

                   CONSOLIDATION, MERGER, SALE OR CONVEYANCE
                   -----------------------------------------

     Section 8.1  Successor Corporation Substituted. In case of any
                  ---------------------------------
consolidation, merger, sale or transfer pursuant to Section 3.10, and following
such an assumption by the successor corporation, such successor corporation
shall succeed to and be substituted for the Issuer, with the same effect as if
it had been named herein.

                                       48
<PAGE>

     Such successor corporation may cause to be signed, and may issue either
in its own name or in the name of the Issuer prior to such succession any or all
of the Securities issuable hereunder that theretofore shall not have been signed
by the Issuer and delivered to the Trustee; and, upon the order of such
successor corporation, instead of the Issuer, and subject to all the terms,
conditions and limitations in this Indenture prescribed, the Trustee shall
authenticate and shall deliver any Securities that previously shall have been
signed and delivered by the officers of the Issuer to the Trustee for
authentication and any Securities that such successor corporation thereafter
shall cause to be signed and delivered to the Trustee for that purpose. All of
the Securities so issued shall in all respects have the same legal rank and
benefit under this Indenture as the Securities theretofore or thereafter issued
in accordance with the terms of this Indenture as though all of such Securities
had been issued at the date of the execution hereof.

     In case of any such consolidation, merger, sale or transfer such changes in
phraseology and form (but not in substance) may be made in the Securities
thereafter to be issued as may be appropriate.

     In the event of any such sale or transfer (other than a transfer by way of
lease) the Issuer or any successor corporation which shall theretofore have
become such in the manner described in this Article 8 shall be discharged from
all obligations and covenants under this Indenture and the Securities and may be
liquidated and dissolved.

     Section 8.2  Opinion of Counsel Provided to Trustee; Officers' Certificate.
                  -------------------------------------------------------------
The Trustee, subject to the provisions of Section 5.1 and Section 5.2 hereof,
shall receive an Officers' Certificate and an Opinion of Counsel as conclusive
evidence that any such consolidation, merger, sale or transfer, and any such
assumption, and any such liquidation or dissolution, complies with the
applicable provisions of this Indenture.

                                  ARTICLE IX

           SATISFACTION AND DISCHARGE OF INDENTURE; UNCLAIMED MONEYS
           ---------------------------------------------------------

     Section 9.1  Satisfaction and Discharge of Indenture. If at any time (a)
                  ---------------------------------------
the Issuer shall have paid or caused to be paid the principal of and premium, if
any, and interest on all the Securities Outstanding hereunder, as and when the
same shall have become due and payable, or (b) the Issuer shall have delivered
to the Trustee for cancellation all Securities theretofore authenticated (other
than any Securities which shall have been destroyed, lost or stolen and which
shall have been replaced or paid as provided in Section 2.7 hereof) or (c)(i)
all such Securities not theretofore delivered to the Trustee for cancellation
shall have become due and payable, or are by their terms to become due and
payable within one year or are to be called for redemption under arrangements
satisfactory to the Trustee for the giving of notice of redemption, and (ii) the
Issuer shall have irrevocably deposited or caused to be deposited with the
Trustee as trust funds the entire amount in cash (other than moneys repaid by
the Trustee or any paying agent to the Issuer in accordance with Section 9.4
hereof) or U.S. Government Obligations, maturing as to principal, premium, if
any, and interest in such amounts and at such times as will insure (without
reinvestment) the availability of cash sufficient, in the opinion of a
nationally recognized firm of independent public accountants expressed in a
written certification thereof delivered to the Trustee, to pay at maturity all
such Securities not theretofore delivered to the

                                       49
<PAGE>

Trustee for cancellation, including principal, premium, if any, and interest due
or to become due to such date of maturity as the case may be, and if, in any
such case, the Issuer shall also pay or cause to be paid all other sums payable
hereunder by the Issuer, then this Indenture shall cease to be of further effect
(except as to (i) rights of registration of transfer and exchange, and the
Issuer's right to optional redemption, (ii) substitution of apparently
mutilated, defaced, destroyed, lost or stolen Securities, (iii) rights of
Holders to receive payments of principal thereof and premium, if any, and
interest thereon, upon the original stated due dates therefor (but not upon
acceleration), (iv) the rights and obligations and immunities of the Trustee
hereunder and (v) the rights of the Holders as beneficiaries hereof with respect
to the property so deposited with the Trustee payable to all or any of them),
and the Trustee, on demand of the Issuer accompanied by an Officers' Certificate
and an Opinion of Counsel and at the cost and expense of the Issuer, shall
execute proper instruments acknowledging such satisfaction of and discharging
this Indenture, provided that the rights of Holders of the Securities to receive
amounts in respect of principal of and premium, if any, and interest on the
Securities held by them shall not be delayed longer than required by then-
applicable mandatory rules or policies of any securities exchange upon which the
Securities are listed.

     The Issuer agrees to reimburse the Trustee for any costs or expenses
thereafter reasonably and properly incurred and to compensate the Trustee for
any services thereafter reasonably and properly rendered by the Trustee in
connection with this Indenture or the Securities.

     Section 9.2  Application by Trustee of Funds Deposited for Payment of
                  --------------------------------------------------------
Securities. Subject to Section 9.4 hereof, all moneys deposited with the Trustee
----------
pursuant to Section 9.1 hereof shall be held in trust and applied by it to the
payment, either directly or through any paying agent (including the Issuer
acting as its own paying agent), to the Holders of the particular Securities for
the payment or redemption of which such moneys have been deposited with the
Trustee, of all sums due and to become due thereon for principal, premium, if
any, and interest; but such money need not be segregated from other funds except
to the extent required by law.

     Section 9.3  Repayment of Moneys Held by Paying Agent. In connection with
                  ----------------------------------------
the satisfaction and discharge of this Indenture all moneys then held by any
paying agent under the provisions of this Indenture shall, upon demand of the
Issuer, be repaid to it or paid to the Trustee and thereupon such paying agent
shall be released from all further liability with respect to such moneys.

     Section 9.4  Return of Moneys Held by Trustee and Paying Agent Unclaimed
                  -----------------------------------------------------------
for Two Years. Any moneys deposited with or paid to the Trustee or any paying
-------------
agent for the payment of the principal of, or premium or interest on any
Security and not applied but remaining unclaimed for two years after the date
upon which such principal, premium or interest shall have become due and payable
shall, upon the written request of the Issuer, be repaid to the Issuer by the
Trustee or such paying agent, and the Holder of such Security shall, unless
otherwise required by mandatory provisions of applicable escheat or abandoned or
unclaimed property laws, thereafter look only to the Issuer for any payment
which such Holder may be entitled to collect, and all liability of the Trustee
or any paying agent with respect to such moneys shall thereupon cease.

                                       50
<PAGE>

     Section 9.5  Defeasance and Discharge of Indenture. The Issuer will be
                  -------------------------------------
deemed to have paid and will be discharged from any and all obligations in
respect of the Securities of a series, on the 123rd day after the deposit
referred to in subparagraph (A) hereof has been made, and the provisions of this
Indenture will no longer be in effect with respect to the Securities of such
series (and the Trustee, at the expense of the Issuer, shall execute proper
instruments acknowledging the same), except as to:

          (a)  rights of registration of transfer and exchange, and the Issuer's
right of optional redemption, (b) substitution of apparently mutilated, defaced,
destroyed, lost or stolen securities, (c) rights of Holders to receive payments
of principal thereof and premium, if any, and interest thereon, (d) the rights,
obligations and immunities of the Trustee hereunder, (e) the rights of the
Holders as beneficiaries hereof with respect to the property so deposited with
the Trustee payable to all or any of them and (f) the obligations of the Issuer
to maintain a place of payment for the Securities of such series under Section
3.1 hereof;

     provided that the following conditions shall have been satisfied:
     --------

               (A)  with reference to this Section 9.5 the Issuer has
          irrevocably deposited or caused to be irrevocably deposited with the
          Trustee (or another trustee satisfying the requirements of Section 5.8
          hereof) as trust funds in trust, specifically pledged as security for,
          and dedicated solely to, the benefit of the Holders of the Securities
          of such series, (i) money in an amount, or (ii) U.S. Government
          Obligations which through the payment of interest and principal in
          respect thereof in accordance with their terms (without reinvestment)
          will provide not later than one day before the due date of any payment
          referred to in clause (x) or (y) of this subparagraph (A) money in an
          amount, or (iii) a combination thereof, sufficient, in the opinion of
          a nationally recognized firm of independent public accountants
          expressed in a written certification thereof delivered to the Trustee,
          to pay and discharge, after payment of all federal, state and local
          taxes or other charges and assessments in respect thereof payable by
          the Trustee, (x) the principal of, premium, if any, and each
          installment of principal and interest on the Outstanding Securities of
          such series at the maturity date of such principal or installment of
          principal or interest and (y) any mandatory sinking fund payments or
          analogous payments applicable to the Securities of such series on the
          day on which such payments are due and payable in accordance with the
          terms of this Indenture and the Securities of such series;

               (B)  the Issuer has delivered to the Trustee (i) an Opinion of
          Counsel to the effect that Holders will not recognize income, gain or
          loss for federal income tax purposes as a result of the Issuer's
          exercise of its option under this Section 9.5 and will be subject to
          federal income tax on the same amount and in the same manner and at
          the same times as would have been the case if such deposit, defeasance
          and discharge had not occurred, which Opinion of Counsel must be based
          on (x) a change in applicable federal income tax law or related
          Treasury Regulations after the date of this Indenture or (y) a ruling
          received by the Issuer from the Internal Revenue Service to the same
          effect and (ii) an Opinion of Counsel to the effect that the
          defeasance trust does not constitute an "investment
                                                   ----------

                                       51
<PAGE>

          company" under the Investment Company Act of 1940, as amended, and
          -------
          after the passage of 123 days following the deposit, the trust fund
          will not be subject to the effect of Section 547 of the U.S.
          Bankruptcy Code or Section 15 of the New York Debtor and Creditor Law;

               (C)  immediately after giving effect to such deposit on a pro
          forma basis, no Event of Default, or event that after the giving of
          notice or lapse of time or both would become an Event of Default,
          shall have occurred and be continuing on the date of such deposit or
          during the period ending on the 123rd day after the date of such
          deposit, and such deposit shall not result in a breach or violation
          of, or constitute a default under, any other agreement or instrument
          to which the Issuer is a party or by which the Issuer is bound; and

               (D)  if at such time the Securities of such series are listed on
          a national securities exchange, the Issuer has delivered to the
          Trustee an Opinion of Counsel to the effect that such Securities will
          not be delisted as a result of such deposit, defeasance and discharge.

     Section 9.6  Defeasance of Certain Obligations. The Issuer may omit to
                  ---------------------------------
comply with any term, provision, or condition set forth in this Indenture in
Sections 3.8 through 3.12, and Section 4.1(d) (with respect to Sections 3.8
through 3.12) and Sections 4.1(c), (e), (i), (j) and (k) shall be deemed not to
be Events of Default on the 123rd day after the deposit referred to in
subparagraph (A) hereof if:

               (A)  with reference to this Section 9.6, the Issuer has
          irrevocably deposited or caused to be irrevocably deposited with the
          Trustee (or another trustee satisfying the requirements of Section 5.8
          hereof) as trust funds in trust, specifically pledged as security for,
          and dedicated solely to, the benefit of the Holders of the Securities,
          (i) money in an amount, or (ii) U.S. Government Obligations which
          through the payment of interest and principal in respect thereof in
          accordance with their terms (without reinvestment) will provide not
          later than one day before the due date of any payment referred to in
          clauses (x) or (y) of this Section 9.6 money in an amount, or (iii) a
          combination thereof, sufficient, in the opinion of a nationally
          recognized firm of independent public accountants expressed in a
          written certification thereof delivered to the Trustee, to pay and
          discharge, after payment of all federal, state and local taxes or
          other charges and assessments in respect thereof payable by the
          Trustee, (x) the principal of, premium, if any, and each installment
          of principal and interest on the Outstanding Securities at the
          maturity date of such principal or installment of principal or
          interest and (y) any mandatory sinking fund payments or analogous
          payments applicable to the Securities on the day on which such
          payments are due and payable in accordance with the terms of this
          Indenture and the Securities;

               (B)  the Issuer has delivered to the Trustee (i) an Opinion of
          Counsel to the effect that Holders will not recognize income, gain or
          loss for federal income tax purposes as a result of the Issuer's
          exercise of its option under this Section 9.6 and will be subject to
          federal income tax on the same amount and in the same

                                       52
<PAGE>

          manner and at the same times as would have been the case if such
          deposit, defeasance and discharge had not occurred, and (ii) an
          Opinion of Counsel to the effect that the defeasance trust does not
          constitute an "investment company" under the Investment Company Act of
                         ------------------
          1940, as amended, and after the passage of 123 days following the
          deposit, the trust fund will not be subject to the effect of Section
          547 of the U.S. Bankruptcy Code or Section 15 of the New York Debtor
          and Creditor Law;

               (C)  immediately after giving effect to such deposit on a pro
          forma basis, no Event of Default, or event that after the giving of
          notice or lapse of time or both would become an Event of Default,
          shall have occurred and be continuing on the date of such deposit or
          during the period ending on the 123rd day after the date of such
          deposit, and such deposit shall not result in a breach or violation
          of, or constitute a default under, any other agreement or instrument
          to which the Issuer is a party or by which the Issuer is bound; and

               (D)  if at such time the Securities are listed on a national
          securities exchange, the Issuer has delivered to the Trustee an
          Opinion of Counsel to the effect that the Securities will not be
          delisted as a result of such deposit, defeasance and discharge.

                                   ARTICLE X

                           MISCELLANEOUS PROVISIONS
                           ------------------------

     Section 10.1  Incorporators, Shareholders, Officers and Directors of Issuer
                   -------------------------------------------------------------
Exempt from Individual Liability.  No recourse under or upon any obligation,
--------------------------------
covenant or agreement contained in this Indenture, or in any Security, or
because of any indebtedness evidenced thereby, shall be had against any
incorporator, as such, or against any past, present or future shareholder,
officer or director, as such, of the Issuer or of any successor, either directly
or through the Issuer or any successor, under any rule of law, statute or
constitutional provision or by the enforcement of any assessment or by any legal
or equitable proceeding or otherwise, all such liability being expressly waived
and released by the acceptance of the Securities by the Holders thereof and as
part of the consideration for the issue of the Securities.

     Section 10.2  Provisions of the Indenture for the Sole Benefit of Parties
                   -----------------------------------------------------------
and Holders.  Nothing in this Indenture or in the Securities, expressed or
-----------
implied, shall give or be construed to give to any Person, other than the
parties hereto and their successors and the Holders (and, where expressly set
forth herein, owners of interests in any Global Security), any legal or
equitable right, remedy or claim under this Indenture or under any covenant or
provision herein contained, all such covenants and provisions being for the sole
benefit of the parties hereto and their successors and the Holders (and, where
expressly set forth herein, owners of interests in any Global Security).

     Section 10.3  Successors and Assigns of Issuer Bound by Indenture.  All the
                   ---------------------------------------------------
covenants, stipulations, promises and agreements in this Indenture contained by
or in behalf of the Issuer shall bind its successors and assigns, whether so
expressed or not.

                                       53
<PAGE>

     Section 10.4  Notices and Demands on Issuer, Trustee and Holders.  Any
                   --------------------------------------------------
notice or demand which by any provision of this Indenture is required or
permitted to be given or served by the Trustee or by the Holders to or on the
Issuer may be given or served by being deposited postage prepaid, first-class
mail (except as otherwise specifically provided herein) addressed (until another
address of the Issuer is filed by the Issuer with the Trustee) to Ameren Energy
Generating Company, P.O. Box 66149 St. Louis, MO 63166, Attention: President.
Any notice, direction, request or demand by the Issuer or any Holder to or upon
the Trustee shall be deemed to have been sufficiently given or made, for all
purposes, if given or made at the Corporate Trust Office or such office or
agency designated for such purpose in Section 3.2 hereof.

     Where this Indenture provides for notice to Holders, such notice shall be
sufficiently given (unless otherwise herein expressly provided) if in writing
and mailed, first-class postage prepaid, to each Holder entitled thereto, at his
last address as it appears in the Securities Register. In any case where notice
to Holders is given by mail, neither the failure to mail such notice, nor any
defect in any notice so mailed, to any particular Holder shall affect the
sufficiency of such notice with respect to other Holders. Where this Indenture
provides for notice in any manner, such notice may be waived in writing by the
Person entitled to receive such notice, either before or after the event, and
such waiver shall be the equivalent of such notice. Waivers of notice by Holders
shall be filed with the Trustee, but such filing shall not be a condition
precedent to the validity of any action taken in reliance upon such waiver.

     In case, by reason of the suspension of or irregularities in regular mail
service, it shall be impracticable to mail notice to the Issuer and Holders when
such notice is required to be given pursuant to any provision of this Indenture,
then any manner of giving such notice as shall be satisfactory to the Trustee
shall be deemed to be a sufficient giving of such notice.

     Section 10.5  Officers' Certificates and Opinions of Counsel; Statements to
                   -------------------------------------------------------------
Be Contained Therein.  Upon any application or demand by the Issuer to the
--------------------
Trustee to take any action under any of the provisions of this Indenture, the
Issuer shall furnish to the Trustee an Officers' Certificate stating that all
conditions precedent provided for in this Indenture relating to the proposed
action have been complied with and an Opinion of Counsel stating that in the
opinion of such counsel all such conditions precedent have been complied with,
except that in the case of any such application or demand as to which the
furnishing of such documents is specifically required by any provision of this
Indenture relating to such particular application or demand, no additional
certificate or opinion need be furnished.

          (a)  Each certificate or opinion provided for in this Indenture and
delivered to the Trustee with respect to compliance with a condition or covenant
provided for in this Indenture shall include a statement that the Person making
such certificate or opinion has read such covenant or condition, (b) a brief
statement as to the nature and scope of the examination or investigation upon
which the statements or opinions contained in such certificate or opinion are
based, (c) a statement that, in the opinion of such Person, he has made such
examination or investigation as is necessary to enable him to express an
informed opinion as to whether or not such covenant or condition has been
complied with and (d) a statement as to whether or not, in the opinion of such
Person, such condition or covenant has been complied with. Any certificate,
statement or opinion of an officer of the Issuer may be based, insofar as it
relates to legal matters, upon a certificate or opinion of or representations by
counsel, unless such officer knows that the

                                       54
<PAGE>

certificate or opinion or representations with respect to the matters upon which
his certificate, statement or opinion may be based as aforesaid are erroneous,
or in the exercise of reasonable care should know that the same are erroneous.
Any certificate, statement or Opinion of Counsel may be based, insofar as it
relates to factual matters (information with respect to which is in the
possession of the Issuer) upon the certificate, statement or opinion of or
representations by an officer or officers of the Issuer, unless such counsel
knows that the certificate, statement or opinion or representations with respect
to the matters upon which his certificate, statement or opinion may be based as
aforesaid are erroneous, or in the exercise of reasonable care should know that
the same are erroneous.

     Any certificate, statement or opinion of an officer of the Issuer or of
counsel may be based, insofar as it relates to accounting matters, upon a
certificate or opinion of or representations by an accountant or firm of
accountants in the employ of the Issuer, unless such officer or counsel, as the
case may be, knows that the certificate or opinion or representations with
respect to the accounting matters upon which his certificate, statement or
opinion may be based as aforesaid are erroneous, or in the exercise of
reasonable care should know that the same are erroneous.

     Any certificate or opinion of any independent firm of public accountants or
Investment Banker filed with the Trustee shall contain a statement that such
firm is independent.

     Section 10.6  Payments Due on Saturdays, Sundays and Holidays.  If the date
                   -----------------------------------------------
of maturity of interest on or principal, or premium, if any, of the Securities
or the date fixed for redemption of any Security shall not be a Business Day,
then payment of interest, principal, or premium need not be made on such date,
but may be made on the next succeeding Business Day with the same force and
effect as if made on the date of maturity or the date fixed for redemption, and
no interest shall accrue for the period after such date.

     Section 10.7  New York Law to Govern.  THIS INDENTURE SHALL, PURSUANT TO
                   ----------------------
SECTION 5-1401 OF THE NEW YORK GENERAL OBLIGATIONS LAW, BE GOVERNED BY THE LAW
OF THE STATE OF NEW YORK, WITHOUT REFERENCE TO THE CHOICE OF LAW PROVISIONS
THEREOF (OTHER THAN SUCH SECTION 5-1401).

     Section 10.8  Counterparts. This Indenture may be executed in any number of
                   ------------
counterparts, each of which shall be an original, but such counterparts shall
together constitute but one and the same agreement.

     Section 10.9  Effect of Headings.  The Article and Section Headings herein
                   ------------------
and the Table of Contents are for convenience only and shall not affect the
construction hereof.

     Section 10.10 Subordinated CIPS Note; AmerenCIPS Acknowledgment; Committed
                   ------------------------------------------------------------
Unit Contribution Agreement; Resources Undertaking. Except with the consent of
--------------------------------------------------
Holders obtained as required by Section 7.2 hereof, the Issuer shall not amend,
modify, terminate or consent to the amendment, modification or termination of
the Subordinated CIPS Note, the AmerenCIPS Acknowledgment, the Committed Unit
Contribution Agreement (other than to make additional generating units subject
to the terms thereof) or the Resources Undertaking until, as to each such
agreement or instrument, all obligations thereunder are performed by the

                                       55
<PAGE>

parties thereto. Notwithstanding the foregoing, the Issuer may prepay or
otherwise reduce in principal amount, in whole or in part, the Subordinated CIPS
Note but only under one or more of the following conditions: (i) upon the
assumption of the obligations and liabilities of AmerenCIPS under up to $182
million of tax-exempt pollution control loan obligations, in which case the
Subordinated CIPS Note shall be reduced by the outstanding principal amount of
such pollution control loan obligations assumed by the Issuer; or (ii) upon
exchange (and use of proceeds therefrom) for debt or equity securities with
terms at least as subordinate as the Subordinated CIPS Note. If the Issuer
effects any such prepayment or reduction in principal amount of the Subordinated
CIPS Note in compliance with the terms and conditions of this Indenture, the
Holders are deemed to acknowledge and agree that such action does not adversely
affect their interests, rights or remedies under this Indenture.

     Section 10.11  Trust Indenture Acts Controls. If and to the extent that any
                    -----------------------------
provision of this Indenture limits, qualifies or conflicts with the duties
imposed by, or with another provision included in this Indenture by operation of
Sections 310 to 318, inclusive, of the Trust Indenture Act, such imposed duties
or incorporated provisions shall control. If any provision of this Indenture
modifies or excludes any provision of the Trust Indenture Act that may be so
modified or excluded, the Indenture as so modified or with such exclusion shall
apply.

                                  ARTICLE XI

                           REDEMPTION OF SECURITIES
                           ------------------------

     Section 11.1  Right of Optional Redemption Price.  Except as otherwise
                   ----------------------------------
provided with respect to the Securities of any series in the Series Supplemental
Indenture relating thereto, the Issuer at its option may, at any time, redeem
the Securities, in whole or in part (if in part, by lot or by such other method
as the Trustee shall deem fair or appropriate), upon payment of a redemption
price equal to the principal amount of the Securities to be redeemed plus
accrued and unpaid interest thereon, if any, plus the Applicable Premium or
other amount as provided in such Series Supplemental Indenture.

     Section 11.2  Notice of Redemption. Notice of redemption to the Holders of
                   --------------------
Securities to be redeemed shall be given by the Issuer by mailing notice of such
redemption by first class mail, postage prepaid, at least 30 days and not more
than 60 days prior to the date fixed for redemption to such Holders of
Securities at their last addresses as they shall appear in the Securities
Register. Failure to give notice by mail, or any defect in the notice to the
Holder of any Security designated for redemption as a whole or in part shall not
affect the validity of the proceedings for the redemption of any other Security.
The notice of redemption to each Holder shall specify that the Securities are
being redeemed pursuant to this Article 11, the date fixed for redemption, the
place or places of payment, the CUSIP and ISIN numbers (as applicable), that
payment will be made upon presentation and surrender of the Securities, that
interest accrued to the date fixed for redemption will be paid as specified in
this Article and that, on and after said date interest thereon or on the
portions thereof to be redeemed will cease to accrue.

     The notice of redemption of Securities to be redeemed at the option of the
Issuer shall be given by the Issuer or, at the Issuer's request, by the Trustee
in the name and at the expense of the Issuer.

                                       56
<PAGE>

     At least one Business Day prior to the redemption date specified in the
notice of redemption given as provided in this Section 11.2, the Issuer shall
deposit with the Trustee or with one or more paying agents (or, if the Issuer is
acting as its own paying agent, set aside, segregate and hold in trust as
provided in Section 3.4 hereof) an amount of money sufficient to redeem on the
redemption date all the Securities so called for redemption.

     Section 11.3  Payment of Securities Called for Redemption. If notice of
                   -------------------------------------------
redemption has been given as above provided, the Securities shall become due and
payable on the date and at the place stated in such notice at the redemption
price, and on and after said date (unless the Issuer shall default in the
payment of such Securities at the redemption price) interest on the Securities
or portions of Securities so called for redemption shall cease to accrue and,
except as provided in Section 5.5 and Section 9.4 hereof, such Securities shall
cease from and after the date fixed for redemption to be entitled to any benefit
or security under this Indenture, and the Holders thereof shall have no right in
respect of such Securities except the right to receive the redemption price
thereof. On presentation and surrender of such Securities at a place of payment
specified in said notice, said Securities shall be paid and redeemed by the
Issuer at the redemption price; provided, that any semi-annual payment of
interest becoming due on the date fixed for redemption shall be payable to the
Holders of such Securities registered as such on the relevant record date
subject to the terms and provisions of Section 2.4 hereof.

     If any Security called for redemption shall not be so paid upon surrender
thereof for redemption, the principal shall, until paid or duly provided for,
bear interest from the date fixed for redemption at the rate borne by the
Security.

                                       57
<PAGE>

     IN WITNESS WHEREOF, the parties hereto have caused this Indenture to be
duly executed as of November 1, 2000.

                                             AMEREN ENERGY GENERATING
                                             COMPANY, as Issuer

                                             By: /s/ Gary L. Rainwater
                                                --------------------------------
                                                Name: Gary L. Rainwater
                                                Title: President

                                             THE BANK OF NEW YORK, as Trustee

                                             By: /s/ Albert Lundy
                                                --------------------------------
                                                Name: Albert Lundy
                                                Title: Qualified Agent

                                       58
<PAGE>

                                                                       EXHIBIT 1
                                                                       ---------

                            Terms of Subordination
                            ----------------------

     Subordinated Parent Borrowings shall contain terms of subordination
substantially similar to the following:

          (a)  The indebtedness evidenced by such Subordinated Parent Borrowings
               shall be subordinate and junior to any and all Senior
               Indebtedness of the Issuer, including, without limitation, the
               Subordinated CIPS Note, now existing or hereafter incurred, in
               respect of (i) borrowings (including renewals and extensions
               thereof) from any one or more banks, insurance companies, pension
               or profit-sharing trusts, or other financial institutions whether
               secured or unsecured, and (ii) Non-Utility Money Pool Borrowings
               and all other borrowings incurred, assumed or guaranteed by the
               Issuer, at any time, before or after the date of such
               Subordinated Parent Borrowings, evidenced by a note, debenture,
               bond or other similar instrument (including capitalized lease and
               purchase money obligations, and/or for the acquisition (whether
               by way of purchase, merger or otherwise) of any business, real
               property or other assets (except assets acquired in the ordinary
               course of business) but excluding obligations other than for
               borrowed money including trade payables and other obligations to
               general creditors), except Indebtedness which, by its terms or
               the terms of the instrument creating or evidencing it, provides
               that such Indebtedness is not superior in right of payment to the
               payment of principal of or any interest on such Subordinated
               Parent Borrowings, or that such Indebtedness is subordinated to
               all other Indebtedness of the Issuer.

          (b)  "Subordinate and junior" as used herein shall mean that in the
               event of:

               (i)    any default in, or violation of, the terms or covenants of
                      any Senior Indebtedness, including, without limitation,
                      any default in payment of principal of, or premium, if
                      any, or interest on, any Indebtedness whenever due
                      (whether by acceleration of maturity or otherwise), and
                      during the continuance thereof, or

               (ii)   the institution of any liquidation, dissolution,
                      bankruptcy, insolvency, reorganization or similar
                      proceeding relating to the Issuer, its property or its
                      creditors as such,

               the holder of Subordinated Parent Borrowings shall not be
               entitled to receive any payment of principal of, or premium, if
               any, or interest on, Subordinated Parent Borrowings until all
               amounts owing in respect of Senior Indebtedness (matured and
               unmatured) shall have been paid in full; and from and after the
               happening of any event described in clause (ii) of

                                       59
<PAGE>

               this paragraph, all payments and distributions of any kind or
               character (whether in cash, securities or property) which, except
               for the subordination provisions hereof, would have been payable
               or distributable to the holder of Subordinated Parent Borrowings
               (whether directly or by reason of Subordinated Parent Borrowings
               being superior to any other indebtedness), shall be made to and
               for the benefit of the holders of Senior Indebtedness (who shall
               be entitled to make all necessary claims therefor) in accordance
               with the priorities of payment thereof until all Senior
               Indebtedness (matured and unmatured) shall have been paid in
               full.

          (c)  Upon the happening of any event described in clauses (i) or (ii)
               of paragraph (b) above, all Indebtedness shall (at the option of
               the holder thereof and subject to the terms thereof) become
               immediately due and payable in full. No act or failure to act on
               the part of the Issuer, and no default under or breach of any
               agreement of the Issuer, whether or not herein set forth, shall
               in any way prevent or limit the holder of any Senior Indebtedness
               from enforcing fully these subordination provisions, irrespective
               of any knowledge or notice which such holder may at any time have
               or be charged with.

          (d)  So long as any Senior Indebtedness shall be outstanding, the
               Issuer shall not, without the prior written consent of all
               holders thereof except as may be otherwise agreed to by such
               holders of such instruments, (i) pay any amount in respect of
               principal of Subordinated Parent Borrowings prior to the stated
               maturity thereof or purchase or redeem Subordinated Parent
               Borrowings in whole or in part, except in compliance with the
               Indenture or (ii) alter or amend any of the terms of this
               paragraph. The Issuer and the holder of Subordinated Parent
               Borrowings shall agree not to alter, amend or waive any of the
               terms of Subordinated Parent Borrowings or any right in respect
               thereto in any manner which might adversely affect the holders of
               Senior Indebtedness without the prior written consent of all such
               holders except as may be otherwise agreed to by such holders in
               such instruments. Anything to the contrary notwithstanding, in
               the event that any payment or distribution is made with respect
               to the indebtedness evidenced by Subordinated Parent Borrowings
               in violation of the terms hereof, any holder hereof receiving
               such payment or distribution shall hold it in trust for the
               benefit of, and shall remit it to, the holders of Senior
               Indebtedness then outstanding in accordance with the priorities
               of payment thereof.

                                       60<PAGE>

                                                                     EXHIBIT 4.2

================================================================================

                         FIRST SUPPLEMENTAL INDENTURE

                         dated as of November 1, 2000

                                      to

                                   INDENTURE

                         dated as of November 1, 2000

                       AMEREN ENERGY GENERATING COMPANY

                                      to

                       THE BANK OF NEW YORK, as Trustee

===============================================================================

                                 $425,000,000

              $225,000,000  7.75% Senior Notes, Series A Due 2005
              $200,000,000  8.35% Senior Notes, Series B Due 2010
<PAGE>

     FIRST SUPPLEMENTAL INDENTURE (the "First Supplemental Indenture"), dated as
of November 1, 2000, to the Indenture, dated as of November 1, 2000 (the
"Original Indenture"), from AMEREN ENERGY GENERATING COMPANY, an Illinois
corporation (together with its successors and assigns, the "Issuer"), its
principal office and mailing address being at One Ameren Plaza, 1901 Chouteau
Avenue, P.O. Box 66149, St. Louis, Missouri 63166-6149, to THE BANK OF NEW YORK,
as trustee (the "Trustee"), its office and mailing address being at 101 Barclay
Street, New York, New York 10286.

                             W I T N E S S E T H:

     WHEREAS, the Issuer and the Trustee have heretofore executed and delivered
the Original Indenture to provide for the issuance from time to time of the
Issuer's Securities (as defined in the Original Indenture) to be issued in one
or more series;

     WHEREAS, Sections 2.1 and 7.1 of the Original Indenture provide, among
other things, that the Issuer and the Trustee may enter into indentures
supplemental to the Original Indenture for, among other things, the purpose of
establishing the designation, form, terms and provisions of Securities of any
series as permitted by Sections 2.1 and 7.1 of the Original Indenture;

     WHEREAS, the Issuer (i) desires the issuance of two (2) series of
Securities to be designated as hereinafter provided and (ii) has requested the
Trustee to enter into this First Supplemental Indenture for the purpose of
establishing the designation, form, terms and provisions of the Securities of
such series;

     WHEREAS, all action on the part of the Issuer necessary to authorize the
issuance of said Securities under the Original Indenture and this First
Supplemental Indenture (the Original Indenture, as supplemented by this First
Supplemental Indenture, being hereinafter called the "Indenture") has been duly
taken; and

     WHEREAS, all acts and things necessary to make said Securities, when
executed by the Issuer and authenticated and delivered by the Trustee as
provided in the Original Indenture, the legal, valid and binding obligations of
the Issuer, and to constitute these presents a valid and binding supplemental
indenture according to its terms, have been done and performed, and the
execution of this First Supplemental Indenture and the creation and issuance
under the Indenture of said Securities have in all respects been duly
authorized, and the Issuer, in the exercise of the legal right and power vested
in it, executes this First Supplemental Indenture and proposes to create,
execute, issue and deliver said Securities;

     NOW, THEREFORE, in order to establish the designation, form, terms and
provisions of, and to authorize the authentication and delivery of, said
Securities, and in consideration of the acceptance of said Securities by the
holders thereof and of other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto agree as
follows:

                                       1
<PAGE>

                                   ARTICLE I

                                  DEFINITIONS
                                  -----------

     Capitalized terms not otherwise defined herein shall have the meanings set
forth in the Original Indenture.

                                  ARTICLE II

                            THE TERMS OF THE NOTES
                            ----------------------

     Section 2.1 Terms of 7.75% Senior Notes, Series A due 2005 and 8.35% Senior
                 ---------------------------------------------------------------
Notes, Series B due 2010. (a) There is hereby created one (1) series of
------------------------
Securities designated: 7.75% Senior Notes, Series A due 2005, in the aggregate
principal amount of $225,000,000 (the " Series A Senior Notes"). Upon delivery
of a written order to the Trustee in accordance with the provisions of Section
2.1 of the Original Indenture, the Trustee shall authenticate and deliver the
Series A Senior Notes. Such written order shall specify the amount of the Series
A Senior Notes to be authenticated and the date on which such Series A Senior
Notes are to be authenticated.

          (b)  There is hereby created one (1) series of Securities designated:
8.35% Senior Notes, Series B due 2010, in the aggregate principal amount of
$200,000,000 (the "Series B Senior Notes" and collectively with the Series A
Senior Notes, the "Senior Notes"). Upon delivery of a written order to the
Trustee in accordance with the provisions of Section 2.1 of the Original
Indenture, the Trustee shall authenticate and deliver the Series B Senior Notes.
Such written order shall specify the amount of the Series B Senior Notes to be
authenticated and the date on which such Series B Senior Notes are to be
authenticated.

          (c)  The Senior Notes of each series shall be substantially in the
form of Exhibit A hereto.

     Section 2.2  Terms of Senior Notes Issued Hereunder in Global Form.
                  -----------------------------------------------------

          (a)  So long as DTC or its nominee is the registered owner or
Holder of a Global Security, DTC or its nominee, as the case may be, will be
considered the sole owner or Holder of the Senior Notes represented by such
Global Security for all purposes under the Original Indenture and under the
Senior Notes. No beneficial owner of an interest in a Global Security will be
able to transfer that interest except in accordance with DTC's applicable
procedures unless the Issuer shall issue certificates for the Senior Notes in
definitive registered form.

          (b)  All payments of the principal of, and interest and additional
amounts and premium, if any, on, a Global Security will be made to DTC or its
nominees, as the registered owners thereof.

          (c)  Transfers between participants in DTC will be effected in the
ordinary way in accordance with DTC rules and will be settled in same-day funds.

                                       2
<PAGE>

          (d)  Certificated definitive Senior Notes of a series may be in
denominations of less than $100,000 to the extent any redemption has reduced
such Holder's aggregate holding of such Senior Notes of the same series to less
than $100,000.

          (e)  If any redemption affecting the Senior Notes of a series would
result in the amount to be paid to a Holder of such affected Senior Note in
respect of such redemption not to equal $1,000 or an integral multiple thereof,
the Issuer shall instruct the Trustee to round the amount to be paid to such
Holder to the nearest $1,000 so that the amount to be paid to such Holder equals
$1,000 or an integral multiple thereof.

          (f)  Beneficial interests in a Global Security of a Series (and any
Securities issued in exchange therefor) will be subject to certain restrictions
on transfer set forth therein and in the Original Indenture and as set forth on
the form of such Global Security. Exhibit B, as referred to in Section 2.4 of
the Original Indenture and Exhibits C, D, E and F, as referred to in Section 2.6
of the Original Indenture are attached hereto as Exhibits B, C, D, E and F,
respectively.

          (g)  Except in the limited circumstances described under Section
2.2(h) below, beneficial interest in a Global Security will only be recorded by
book-entry and owners of beneficial interest in a Global Security will not be
entitled to receive physical delivery of certificates representing Securities.

          (h)  If (i) the Issuer notifies the Trustees in writing that DTC or
any successor depository is unwilling or unable to continue as a depository for
a Global Security or ceases to be a "clearing agency" registered under the
Exchange Act and a successor depository is not appointed by the Issuer within 90
days of such notice, (ii) the Issuer, at its option, notifies the Trustee in
writing that it elects to cause the issuance of the Securities issued hereunder
to be in certificated form or (iii) during an Event of Default, a holder of a
beneficial interest in a Global Security requests the issuance of certificated
Securities representing such holder's interest then, the Issuer shall issue
certificates for the Securities in definitive registered form substantially in
the form attached hereto in exchange for the Global Security outstanding.

          (i)  The holder of a certificated definitive registered Security may
transfer such Security in whole or in part by surrendering it at the Corporate
Trust Office of the Trustee in accordance with the terms of the Indenture and
such Security. Upon the transfer, exchange or replacement of definitive
Securities, the Issuer will deliver only definitive Securities that bear a
restrictive legend unless there is delivered to the Issuer such satisfactory
evidence, which may include an opinion of counsel, as may reasonably be required
by the Issuer, that neither the legend nor the restrictions on transfer set
forth therein are required to ensure compliance with the provisions of the
Securities Act.

     Section 2.3  Interest, Principal, Maturity Date and Regular Record Date.
                  ----------------------------------------------------------
Each Senior Note shall bear interest on the unpaid principal amount thereof from
time to time outstanding from the date of authentication thereof until such
amount is paid in full at the rate of interest set forth in the form of such
Senior Note attached hereto. The principal amount of each Senior Note shall be
due and payable at maturity as set forth in the form of Senior Note attached
hereto.

                                       3
<PAGE>

     Payment of principal of, premium, if any, and interest on the Senior Notes
of each series shall be made, as provided in Sections 2.4, 2.10, 3.2 and 3.4 of
the Original Indenture except that the final payment of principal of any series
of the Senior Notes shall be made on the due date therefor to the account of the
Holder as such account shall appear in the Security Register, which amount shall
be payable upon presentation and surrender of such Senior Note at the office of
the Issuer.

     Each Senior Note of a series shall mature on the date and in the amounts
set forth thereon.

     The record date applicable to the Senior Notes of each series issued
hereunder shall be as set forth in the form of Senior Note of such series
attached hereto.

     All payments of principal and interest with respect to certificated Senior
Notes will be made by bank check mailed on the interest payment date to the
address of such Holder on the Security Register or, for Holders of at least U.S.
$1,000,000 in aggregate principal amount of Senior Notes of a series, by wire
transfer on the interest payment date to a dollar account maintained by the
payee with a bank in The City of New York; provided, that a written request from
                                           --------
such Holder to such effect designating such account is received by the Trustee
and the Issuer or the paying agent no later than the record date immediately
preceding such Interest Payment Date.  Unless such designation is revoked, any
such designation made by such person with respect to such certificated Senior
Notes will remain in effect with respect to any future payments with respect to
such certificated Senior Note payable to such person.

     Section 2.4  Redemption.
                  ----------

          (a)  Optional Redemption.
               -------------------

          The Senior Notes of either series issued hereunder are subject to
optional redemption, in whole or in part, at any time at the option of the
Issuer at a redemption price equal to the outstanding principal amount of the
Senior Notes of such series being so redeemed plus accrued and unpaid interest
thereon to the date fixed for redemption together with the Applicable Premium
applicable thereto.

          (b)  Applicable Premium.
               ------------------

          As used herein, "Applicable Premium" means an amount calculated as of
the date (the "Determination Date") fixed for the redemption of the Senior Notes
of such series as follows:

          (i)  the average life of the remaining scheduled payments of principal
          in respect of Outstanding Senior Notes of such series (the "Remaining
                                                                      ---------
          Average Life") shall be calculated as of the Determination Date;
          ------------

          (ii) the yield to maturity calculated as of a date not more than five
          days prior to the Determination Date for the United States Treasury
          security having an average life equal to the Remaining Average Life of
          such series and trading in the secondary market at the price closest
          to the principal amount thereof (the "Primary Issue"); provided,
                                                -------------    --------
          however, that if no United States Treasury security has an average
          -------
          life equal to the Remaining Average Life of such series, the yields
          (the "Other Yields") for the two maturities of United States treasury
                ------------
          securities having average lives most closely corresponding to such
          Remaining Average Life

                                       4
<PAGE>

          and trading in the secondary market at the price closest to the
          principal amount thereof shall be calculated, and the yield to
          maturity for the Primary Issue shall be the yield interpolated or
          extrapolated from such Other Yields on a straight line basis, rounding
          in each of such relevant periods to the nearest month;

          (iii) the discounted present value of the then remaining scheduled
          payments of principal and interest (but excluding that portion of any
          scheduled payment of interest that is actually due and paid on the
          Determination Date) in respect of the Outstanding Senior Notes of such
          series shall be calculated as of the Determination Date using a
          discount factor equal to the sum of (x) the yield to maturity for the
          Primary Issue, plus (y) 25 basis points; and
                         ----

          (iv)  the amount of Applicable Premium in respect of the Senior Notes
          of such series to be redeemed shall be an amount equal to (x) the
          discounted present value of such Senior Notes to be redeemed
          determined in accordance with clause (iii) above, minus (y) the unpaid
                                                            -----
          principal amount of such Senior Notes; provided, however, that the
                                                 --------  -------
          Applicable Premium shall not be less than zero; and

          (v)   such calculation shall be made by an Investment Banker.

                                  ARTICLE III

                                 MISCELLANEOUS
                                 -------------

     Section 3.1  Execution of Supplemental Indenture.  This First Supplemental
                  -----------------------------------
Indenture is executed and shall be construed as an indenture supplemental to the
Original Indenture and, as provided in the Original Indenture, this First
Supplemental Indenture forms a part thereof.

     Section 3.2  Concerning the Trustee. The Trustee shall not be responsible
                  ----------------------
in any manner for or with respect to the validity or sufficiency of this First
Supplemental Indenture, or the due execution hereof by the Issuer, or for or
with respect to the recitals and statements contained herein, all of which
recitals and statements are made solely by the Issuer.

     Section 3.3  Counterparts. This First Supplemental Indenture may be
                  ------------
executed in any number of counterparts, each of which when so executed shall be
deemed to be an original; but all such counterparts shall together constitute
but one and the same instrument.

     Section 3.4  GOVERNING LAW. THIS FIRST SUPPLEMENTAL INDENTURE AND EACH
                  -------------
SENIOR NOTE ISSUED HEREUNDER SHALL, PURSUANT TO SECTION 5-1401 OF THE NEW YORK
GENERAL OBLIGATIONS LAW, BE GOVERNED BY THE LAW OF THE STATE OF NY, WITHOUT
REFERENCE TO THE CHOICE OF LAW PROVISIONS THEREOF (OTHER THAN SUCH SECTION 5-
1401).

                                       5
<PAGE>

     IN WITNESS WHEREOF, the parties hereto have caused this First Supplemental
Indenture to be duly executed as of November 1, 2000.

                               AMEREN ENERGY GENERATING COMPANY,
                               as Issuer

                               By:        /s/ Gary L. Rainwater
                                   ----------------------------------------
                                   Name:  Gary L. Rainwater
                                   Title: President

                               THE BANK OF NEW YORK, as Trustee

                               By:        /s/ Albert Lundy
                                   ----------------------------------------
                                   Name:  Albert Lundy
                                   Title: Qualified Agent

<PAGE>

                                                                       EXHIBIT A

                               FORM OF SECURITY

     [INCLUDE IF SECURITY IS A GLOBAL SECURITY DEPOSITED WITH THE U.S.
DEPOSITARY -- UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED
REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY TO THE ISSUER OR ITS AGENT FOR
REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IN
EXCHANGE FOR THIS CERTIFICATE OR ANY PORTION HEREOF IS REGISTERED IN THE NAME OF
CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED
REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY OR SUCH OTHER NAME AS IS
REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY (AND
ANY PAYMENT HEREON IS MADE TO CEDE & CO.), ANY TRANSFER, PLEDGE OR OTHER USE
HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON OTHER THAN THE DEPOSITORY
TRUST COMPANY OR A NOMINEE THEREOF IS WRONGFUL INASMUCH AS THE REGISTERED OWNER
HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

     TRANSFERS OF THIS GLOBAL SECURITY SHALL BE LIMITED TO TRANSFERS IN WHOLE,
BUT NOT IN PART, TO NOMINEES OF THE DEPOSITORY TRUST COMPANY OR TO A SUCCESSOR
THEREOF OR SUCH SUCCESSOR'S NOMINEE AND TRANSFERS OF PORTIONS OF THIS GLOBAL
SECURITY SHALL BE LIMITED TO TRANSFERS MADE IN ACCORDANCE WITH THE RESTRICTIONS
SET FORTH IN SECTION 2.6 OF THE INDENTURE REFERRED TO ON THE REVERSE HEREOF.]

     THIS NOTE (OR ITS PREDECESSOR) WAS ORIGINALLY ISSUED IN A TRANSACTION
EXEMPT FROM REGISTRATION UNDER THE UNITED STATES SECURITIES ACT OF 1933, AS
AMENDED (THE "SECURITIES ACT"), AND MAY NOT BE OFFERED, SOLD, PLEDGED OR
OTHERWISE TRANSFERRED IN THE ABSENCE OF SUCH REGISTRATION OR AN APPLICABLE
EXEMPTION THEREFROM AND IN ANY EVENT MAY BE SOLD OR OTHERWISE TRANSFERRED ONLY
IN ACCORDANCE WITH THE INDENTURE, COPIES OF WHICH ARE AVAILABLE FOR INSPECTION
AT THE CORPORATE TRUST OFFICE OF THE TRUSTEE IN NEW YORK.

     EACH PURCHASER OF THIS NOTE IS HEREBY NOTIFIED THAT THE SELLER MAY BE
RELYING ON THE EXEMPTION FROM THE PROVISIONS OF SECTION 5 OF THE SECURITIES ACT
PROVIDED BY RULE 144A THEREUNDER. EACH HOLDER OF THIS NOTE REPRESENTS TO AMEREN
ENERGY GENERATING COMPANY THAT (a) SUCH HOLDER WILL NOT SELL, PLEDGE OR
OTHERWISE TRANSFER THIS NOTE (WITHOUT THE CONSENT OF AMEREN ENERGY GENERATING
COMPANY) OTHER THAN (i) TO A QUALIFIED INSTITUTIONAL BUYER IN A TRANSACTION
COMPLYING WITH RULE 144A UNDER THE SECURITIES ACT, (ii) IN ACCORDANCE WITH RULE
144 UNDER THE SECURITIES ACT, (iii) OUTSIDE THE UNITED STATES IN A TRANSACTION
MEETING THE REQUIREMENTS OF REGULATION S UNDER THE SECURITIES ACT, (iv) PURSUANT
TO ANOTHER AVAILABLE EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT,
SUBJECT, IN THE CASE OF

<PAGE>

CLAUSES (ii), (iii) OR (iv), TO THE RECEIPT BY AMEREN ENERGY GENERATING COMPANY
OF AN OPINION OF COUNSEL OR SUCH OTHER EVIDENCE ACCEPTABLE TO AMEREN ENERGY
GENERATING COMPANY THAT SUCH RESALE, PLEDGE OR TRANSFER IS EXEMPT FROM THE
REGISTRATION REQUIREMENTS OF THE SECURITIES ACT OR (v) PURSUANT TO AN EFFECTIVE
REGISTRATION STATEMENT AND THAT (b) THE HOLDER WILL, AND EACH SUBSEQUENT HOLDER
IS REQUIRED TO, NOTIFY ANY PURCHASER OF THIS NOTE OF THE RESALE RESTRICTIONS
REFERRED TO HEREIN AND DELIVER TO THE TRANSFEREE (OTHER THAN A QUALIFIED
INSTITUTIONAL BUYER) PRIOR TO THE SALE A COPY OF THE TRANSFER RESTRICTIONS
APPLICABLE HERETO (COPIES OF WHICH MAY BE OBTAINED FROM THE TRUSTEE).

                         [FORM OF FACE OF SENIOR NOTE]

                           CUSIP [      ][   ][   ]

                                 [Common Code]
                               [ISIN][        ]

No.

                                       $
                       AMEREN ENERGY GENERATING COMPANY
                          * % Senior Notes Due 20 **

     Ameren Energy Generating Company (the "Issuer"), for value received hereby
                                            ------
promises to pay to ___________________ or registered assigns the principal sum
of ____________ Dollars at the Issuer's office or agency for said purpose as
provided in the Indenture referred to herein, on November 1,**      in such coin
or currency of the United States of America as at the time of payment shall be
legal tender for the payment of public and private debts, and to pay interest,
semi-annually in arrears on May 1 and November 1 of each year, commencing May 1,
2001, on said principal sum in like coin or currency at the rate per annum set
forth above at said offices or agencies from the date of original issuance or
the most recent interest payment date to which interest on the Senior Notes has
been paid or duly provided for.  Notwithstanding the foregoing, if the date
hereof is after April 15 or October 15, as the case may be, and before the
following May 1 or November 1, this Senior Note shall bear interest from such
May 1 or November 1; provided, that if the Issuer shall default in the payment
of interest due on such May 1 or November 1, then this Senior Note shall bear
interest from the next preceding May 1 or November 1 to which interest on the
Senior Notes has been paid or duly provided for.  The interest so payable on any
May 1 or November 1 will, except as otherwise provided in the Indenture referred
to on the reverse hereof, be paid to the Person in whose name this Senior Note
is registered at the close of business on the 15th day of April or the 15th day
of October preceding such May 1 or November 1, whether or not such day is a
Business Day; provided, that

____________________

*    Insert 7.75% or 8.35% as applicable.

**   Insert 2005 or 2010 as applicable.

<PAGE>

principal, premium, if any, and interest shall be paid by mailing on the
interest payment date a check for such to or upon the written order of the
registered Holders of Senior Notes entitled thereto at their last address as it
appears on the Senior Notes Register or, upon written application to the Trustee
by a Holder of $1,000,000 or more in aggregate principal amount of Senior Notes,
by wire transfer on the interest payment date of immediately available funds to
an account maintained by such Holder with a bank or other financial institution.
Interest on this Senior Note shall be computed on the basis of a 360-day year
comprised of twelve 30-day months. Additional Interest shall accrue on this
Senior Note under the circumstances provided for in the Registration Rights
Agreement.

     Interest on overdue principal and (to the extent permitted by applicable
law) on overdue installments of interest (including without limitation during
the 5-day period referred to in Section 4.1(b) of the Indenture) shall accrue at
the rate per annum set forth above.

     Reference is made to the further provisions set forth on the reverse
hereof. Such further provisions shall for all purposes have the same effect as
though fully set forth at this place.

<PAGE>

     This Senior Note shall not be entitled to any benefit under the Indenture,
or be valid or obligatory, until the certificate of authentication hereon shall
have been duly signed by the Trustee acting under the Indenture.

     IN WITNESS WHEREOF, the Issuer has caused this instrument to be duly
executed.

                                        THE BANK OF NEW YORK, as Trustee

                                        By: ______________________________
                                            Name:
                                            Title:
(SEAL)
Attested:

By: ______________________________
Name:
Title:

<PAGE>

                       [FORM OF REVERSE OF SENIOR NOTE]

                       AMEREN ENERGY GENERATING COMPANY

                          * % Senior Notes Due 20  **

     This Senior Note is one of a duly authorized issue of debt securities of
the Issuer, limited to the aggregate principal amount of $          ***
(except as otherwise provided in the Indenture mentioned below), issued or to be
issued pursuant to an Indenture dated as of November 1, 2000 as supplemented by
the First Supplemental Indenture dated as of November 1, 2000 (as so
supplemented, the "Indenture"), duly executed and delivered by the Issuer to the
                   ---------
Trustee.  Reference is hereby made to the Indenture and all indentures
supplemental thereto for a description of the rights, limitations of rights,
obligations, duties and immunities thereunder of the Trustee, the Issuer and the
Holders (the words "Holders" or "Holder" meaning the registered holders or
                    -------      ------
registered holder) of the Senior Notes.  Capitalized terms used herein, but not
otherwise defined herein, shall have the meanings assigned to them in the
Indenture.

     In case an Event of Default shall have occurred and be continuing, the
principal of all the Securities may be declared due and payable, in the manner
and with the effect, and subject to the conditions, provided in the Indenture.
The Indenture provides that in certain events such declaration and its
consequences may be waived by the Holders of a majority in aggregate principal
amount of the Securities then Outstanding and that, prior to any such
declaration, such Holders may waive any past default under the Indenture and its
consequences except a default in the payment of principal of or premium, if any,
or interest on any of the Securities and as otherwise provided in the Indenture.
Any such consent or waiver by the Holder of this Senior Note (unless revoked as
provided in the Indenture) shall be conclusive and binding upon such Holder and
upon all future Holders and owners of this Senior Note and any Security which
may be issued in exchange or substitution hereof, whether or not any notation
thereof is made upon this Senior Note or such other Security.

     The Indenture permits the Issuer and the Trustee, with the consent of the
Holders of not less than a majority in aggregate principal amount of the
Securities of all series at the time Outstanding considered as one class,
evidenced as in the Indenture provided, to modify the Indenture or any
supplemental indentures or the rights of the Holders of the Senior Notes;
provided that no such modification shall (a) change the Stated Maturity of the
--------
principal of, or any installment of principal of or interest on, any Security,
or reduce the principal amount thereof, or reduce the rate or extend the time of
payment of interest thereon, or reduce any amount payable on redemption thereof
or impair or affect the right of any Holder of the Security to institute suit
for the payment thereof without the consent of the Holder of each Security so
affected; or (b)(i) reduce the aforesaid percentage of Securities, the consent
of the Holders of which is required for any such modification or the percentage
of Securities, the consent of Holders of

________________
*    Insert 7.75% or 8.35% as applicable.

**   Insert 2005 or 2010 as applicable.

***  Insert $225,000,000 or $200,000,000 as applicable.
<PAGE>

which is required for any waiver provided for in the Indenture; (ii) change any
obligation of the Issuer to maintain an office or agency for payment of and
transfer and exchange of the Securities; or (iii) make certain changes to
provisions relating to waiver or to the provision for supplementing the
Indenture; in each case without the consent of the Holders of all Securities
then Outstanding.

     No reference herein to the Indenture and no provision of this Senior Note
or of the Indenture shall alter or impair the obligation of the Issuer, which is
absolute and unconditional, to pay the principal of and premium, if any, and
interest on this Senior Note at the place, times, and rate, and in the currency,
herein prescribed.

     The Senior Notes are issuable only as registered Senior Notes without
coupons in denominations of $100,000 and any integral multiple of $1,000 in
excess thereof.

     At the office or agency of the Issuer referred to on the face hereof and in
the manner and subject to the limitations provided in the Indenture, Senior
Notes may be presented for exchange for a like aggregate principal amount of
Senior Notes of other authorized denominations.

     Upon due presentment for registration of transfer of this Senior Note at
the above-mentioned office or agency of the Issuer, a new Senior Note or Senior
Notes of authorized denominations, for a like aggregate principal amount, will
be issued to the transferee as provided in the Indenture.  No service charge
shall be made for any such transfer, but the Issuer may require payment of a sum
sufficient to cover any tax or other governmental charge that may be imposed in
relation thereto.

     The Senior Notes may be redeemed in whole or in part (if in part, by lot or
by such other method as the Trustee shall deem fair or appropriate) prior to
Stated Maturity at the option of the Issuer, upon mailing a notice of such
redemption not less than 30 nor more than 60 days prior to the date fixed for
redemption to the Holders of Senior Notes, all as provided in the Indenture, at
a redemption price equal to the principal amount thereof plus accrued and unpaid
interest thereon, if any, to the date of redemption, plus the Applicable
Premium.

     Subject to payment by the Issuer of a sum sufficient to pay the amount due
on redemption, interest on this Senior Note shall cease to accrue upon the date
duly fixed for redemption of this Senior Note.

     The Issuer, the Trustee, and any authorized agent of the Issuer or the
Trustee, may deem and treat the registered Holder hereof as the absolute owner
of this Senior Note (whether or not this Senior Note shall be overdue and
notwithstanding any notation of ownership or other writing hereon made by anyone
other than the Issuer or the Trustee or any authorized agent of the Issuer or
the Trustee), for the purpose of receiving payment of, or on account of, the
principal hereof and premium, if any, and, subject to the provisions on the face
hereof, interest hereon and for all other purposes, and neither the Issuer nor
the Trustee nor any authorized agent of the Issuer or the Trustee shall be
affected by any notice to the contrary.

     No recourse shall be had for the payment of the principal of, or premium,
if any, or the interest on this Senior Note, for any claim based hereon, or
otherwise in respect hereof, or based

                                       2
<PAGE>

on or in respect of the Indenture or any indenture supplemental thereto, against
any incorporator, shareholder, officer or director, as such, past, present or
future, of the Issuer or of any successor corporation, either directly or
through the Issuer or any successor corporation, whether by virtue of any
constitution, statute or rule of law or by the enforcement of any assessment or
penalty or otherwise, all such liability being, by the acceptance hereof and as
part of the consideration for the issue hereof, expressly waived and released.

                                       3
<PAGE>

               [FORM OF TRUSTEE'S CERTIFICATE OF AUTHENTICATION]

Dated:

     This is one of the Senior Notes referred to in the within-mentioned
Indenture.

                                                THE BANK OF NEW YORK, as Trustee

                                                By: ____________________________
                                                          Authorized Signatory

                                       4
<PAGE>

                             [FORM OF ASSIGNMENT]

I or we assign and transfer this Security to:

             (Insert assignee's social security or tax I.D. number)

_______________________________________________________
_______________________________________________________
_______________________________________________________
_______________________________________________________
(Print or type name, address and zip code of assignee)

and irrevocably appoint:

_______________________________________________________
_______________________________________________________

Agent to transfer this Security on the books of the Issuer.  The Agent may
substitute another to act for him.

Date: _____________________       Your Signature: ___________________

                                   (Sign exactly as your name
                                   appears on the other side of
                                   this Security)

               *Signature Guarantee:________________________

               *Signatures must be guaranteed by an "eligible guarantor
          institution" meeting the requirements of the Registrar, which
          requirements include membership or participation in STAMP or such
          other "signature guarantee program" as may be determined by the
          Registrar in addition to, or in substitution for, STAMP, all in
          accordance with the Securities Exchange Act of 1934.

                                       5
<PAGE>

                                                                       EXHIBIT B

                     FORM OF RESTRICTED PERIOD CERTIFICATE
                       AMEREN ENERGY GENERATING COMPANY

                                    [DATE]

The Depository Trust Company
[Address]

The Bank of New York,
 as Trustee
[Attn: Corporate Trust
101 Barclay Street
New York, New York 10286]

     Re:  Ameren Energy Generating Company        % Senior Notes Due 20__
          ---------------------------------------------------------------

Ladies and Gentlemen:

     Reference is hereby made to the Indenture dated as of November 1, 2000 (the
"Indenture") from Ameren Energy Generating Company, to The Bank of New York, as
 ---------
Trustee.  Capitalized terms used and not defined herein shall have the meanings
given them in the Indenture.

     This letter is related to U.S. $______________ principal amount of Senior
Notes represented by the Restricted Regulation S Global Security, held by the
Trustee pursuant to Section 2.4 of the Indenture.  We hereby certify that the
offering of the Senior Notes has closed and that the restricted period (as
defined in Regulation S) with respect to the offer and sale of the Senior Notes
has terminated.

                                                THE BANK OF NEW YORK, as Trustee

                                                By: ____________________________
                                                         Authorized Signatory

cc:    [Euroclear]
       [CLEARSTREAM]
<PAGE>

                                                                       EXHIBIT C

                         FORM OF TRANSFER CERTIFICATE
            FOR TRANSFER OR EXCHANGE FROM RULE 144A GLOBAL SECURITY
       OR IAI GLOBAL SECURITY TO RESTRICTED REGULATION S GLOBAL SECURITY

                      (Transfers or exchanges pursuant to
                     Section 2.6(b)(ii) of the Indenture)

The Bank of New York,
as Trustee
[Attn: Corporate Trust
101 Barclay Street
New York, New York 10286]

     Re:  Ameren Energy Generating Company      % Senior Notes
          Due 20    (the "Senior Notes")
          ------------------------------------------------------

     Reference is hereby made to the Indenture dated as of November 1, 2000 (the
"Indenture") from Ameren Energy Generating Company to The Bank of New York, as
 ---------
Trustee.  Capitalized terms used but not defined herein shall have the meanings
given to them in the Indenture.

     This letter relates to U.S.$______________ principal amount of Senior Notes
which are held in the form of the [Rule 144A] [IAI] Global Security (CUSIP No.[
][           ]) with the U.S. Depositary in the name of [insert name of
transferor] (the "Transferor").  The Transferor has requested a transfer or
                  ----------
exchange of such beneficial interest for an interest in the Restricted
Regulation S Global Security (CUSIP No.            ) to be held with [Euroclear]
[Clearstream] (Common Code ________) through the U.S. Depositary.

     In connection with such request and in respect of such Senior Notes, the
Transferor does hereby certify that such transfer or exchange has been effected
in accordance with the transfer restrictions set forth in the Indenture and the
Senior Notes and pursuant to and in accordance with Regulation S under the
Securities Act, and accordingly the Transferor does hereby certify that:

     (1) the offer of the Senior Notes was not made to a person in the United
States;

     [(2)  at the time the buy order was originated, the transferee was outside
the United States or the Transferor and any person acting on its behalf
reasonably believed that the transferee was outside the United States,]*

     [(2)  the transaction was executed in, on or through the facilities of a
designated offshore securities market and neither the Transferor nor any person
acting on its behalf knows that the transaction was pre-arranged with a buyer in
the United States,]*

     (3) no directed selling efforts have been made in contravention of the
requirements of Rule 903(b) or 904(b) of Regulation S, as applicable, and
<PAGE>

     (4) the transaction is not part of a plan or scheme to evade the
registration requirements of the Securities Act.

     This certificate and the statements contained herein are made for your
benefit and the benefit of the Issuer and the Initial Purchasers.

                                                [Insert Name of Transferor]

                                                By:_____________________________
                                                   Name:
                                                   Title:

Dated:____________, 2000

cc:  Ameren Energy Generating Company

___________________
*  Insert one of these two provisions, which come from the definition of
"offshore transactions" in Regulation S.

                                       2
<PAGE>

                                                                       EXHIBIT D

                         FORM OF TRANSFER CERTIFICATE
            FOR TRANSFER OR EXCHANGE FROM RULE 144A GLOBAL SECURITY
      OR IAI GLOBAL SECURITY TO UNRESTRICTED REGULATION S GLOBAL SECURITY

                      (Exchanges or transfers pursuant to
                     Section 2.6(b)(iii)of the Indenture)

The Bank of New York,
as Trustee
[Attn: Corporate Trust
101 Barclay Street
New York, New York  10286]

     Re:  Ameren Energy Generating Company      % Senior Notes
     Due 20    (the "Senior Notes")
     -------------------------------------------------------------

     Reference is hereby made to the Indenture dated as of November 1, 2000 (the
"Indenture") from Ameren Energy Generating Company to The Bank of New York, as
 ---------
Trustee.  Capitalized terms used but not defined herein shall have the meanings
given to them in the Indenture.

     This letter relates to U.S.$______________ principal amount of Senior Notes
which are held in the form of the [Rule 144A] [IAI] Global Security (CUSIP No. [
][            ]) with the U.S. Depositary in the name of [insert name of
transferor] (the "Transferor").  The Transferor has requested an exchange or
                  ----------
transfer of such beneficial interest in the Senior Notes for an interest in the
Unrestricted Regulation S Global Security (CUSIP No.            ).

     In connection with such request and in respect of such Senior Notes, the
Transferor does hereby certify that such exchange or transfer has been effected
in accordance with the transfer restrictions set forth in the Indenture and the
Senior Notes and,

     (i) with respect to transfers made in reliance on Regulation S under the
Securities Act, the Transferor does hereby certify that:

     (1) the offer of the Senior Notes was not made to a person in the United
States;

     [(2)  at the time the buy order was originated, the transferee was outside
the United States or the Transferor and any person acting on its behalf
reasonably believed that the transferee was outside the United States,]*

     [(2)  the transaction was executed in, on or through the facilities of a
designated offshore securities market and neither the Transferor nor any person
acting on its behalf knows that the transaction was pre-arranged with a buyer in
the United States,]*

     (3) no directed selling efforts have been made in contravention of the
requirements of Rule 903(b) or 904(b) of Regulation S, as applicable, and
<PAGE>

     (4)   the transaction is pursuant to and in accordance with Regulation S
and is not part of a plan or scheme to evade the registration requirements of
the United States Securities Act of 1933, as amended (the "Securities Act");

     (ii)  with respect to transfers made in reliance on Rule 144 under the
Securities Act, the transferor does hereby certify that the Senior Notes are
being transferred in a transaction permitted by Rule 144 under the Securities
Act,

     (iii) with respect to transfers made in reliance on another exemption from
the Securities Act (including without limitation Rule 144A), the transferor does
hereby certify that the following is the basis for the exemption:
_________________, or

     (iv)  with respect to an exchange, the transferor does hereby certify that
either (x) the Security being exchanged is not a "restricted security" as
defined in Rule 144 under the Securities Act or (y) the exchange is being made
to facilitate a contemporaneous transfer that complies with Section 2.6(b)(iii)
of the Indenture.

     This certificate and the statements contained herein are made for your
benefit and the benefit of the Issuer and the Initial Purchasers.

                                                [Insert Name of Transferor]

                                                By:_____________________________
                                                   Name:
                                                   Title:
Dated:_______________, 2000

cc:  Ameren Energy Generating Company

______________________
*  Insert one of these two provisions, which come from the definition of
"offshore transactions" in Regulation S.

                                       2
<PAGE>

                                                                       EXHIBIT E

             FORM OF TRANSFER CERTIFICATE FOR TRANSFER OR EXCHANGE
          FROM RESTRICTED REGULATION S GLOBAL SECURITY, UNRESTRICTED
                        REGULATION S GLOBAL SECURITY OR
               IAI GLOBAL SECURITY TO RULE 144A GLOBAL SECURITY

                      (Exchanges or transfers pursuant to
                     Section 2.6(b)(iv) of the Indenture)

The Bank of New York,
as Trustee
[Attn: Corporate Trust
101 Barclay Street
New York, New York 10286]

     Re:  Ameren Energy Generating Company      % Senior Notes
     Due 20    (the "Senior Notes")
     ------------------------------------------------------------

     Reference is hereby made to the Indenture dated as of November 1, 2000 (the
"Indenture") from Ameren Energy Generating Company to The Bank of New York, as
 ---------
Trustee.  Capitalized terms used but not defined herein shall have the meanings
given to them in the Indenture.

     This letter relates to U.S. $______________ principal amount of Senior
Notes which are held in the form of the [[Restricted][Unrestricted] Regulation S
Global Security (CUSIP No.            ) with [Euroclear] [Clearstream].*
(Common Code _______)] [IAI Global Security (CUSIP No.            )] through the
U.S. Depositary in the name of [insert name of transferor] (the "Transferor").
                                                                 ----------
The Transferor has requested a transfer or exchange of such beneficial interest
in the Senior Notes for an interest in the Rule 144A Global Security.

     In connection with such request, and in respect of such Senior Notes, the
Transferor does hereby certify that such Senior Notes are being transferred or
exchanged in accordance with (i) the transfer restrictions set forth in the
Senior Notes and (ii) Rule 144A under the Securities Act to a transferee that
the Transferor reasonably believes is purchasing the Senior Notes for its own
account or an account with respect to which the transferee exercises sole
investment discretion and the transferee and any such account is a "qualified
institutional buyer" within the meaning of Rule 144A, in each case in a
transaction meeting the requirements of Rule 144A and in accordance with any
applicable securities laws of any state of the United States or any other
jurisdiction.

___________________
*  Select appropriate depositary.
<PAGE>

     This certificate and the statements contained herein are made for your
benefit and the benefit of the Issuer and the Initial Purchasers.

                                                [Insert Name of Transferor]

                                                By:_____________________________
                                                   Name:
                                                   Title:

Dated:___________, 2000

cc:  Ameren Energy Generating Company
<PAGE>

                                                                       EXHIBIT F

                   FORM OF TRANSFER CERTIFICATE FOR TRANSFER
       OR EXCHANGE FROM RULE 144A GLOBAL SECURITY, RESTRICTED REGULATION
         GLOBAL SECURITY OR UNRESTRICTED REGULATION S GLOBAL SECURITY
                            TO IAI GLOBAL SECURITY

                      (Exchanges or transfers Pursuant to
                      Section 2.6(b)(v) of the Indenture)

The Bank of New York,
as Trustee
[Attn: Corporate Trust
101 Barclay Street
New York, New York 10286]

     Re:  Ameren Energy Generating Company      % Senior Notes
     Due 20    (the "Senior Notes")
     ------------------------------------------------------------

     Reference is hereby made to the Indenture dated as of November 1, 2000 (the
"Indenture") from Ameren Energy Generating Company to The Bank of New York, as
 ---------
Trustee.  Capitalized terms used but not defined herein shall have the meanings
given to them in the Indenture.

     This letter relates to U.S.$______________ principal amount of Senior Notes
which are held in the form of the [Rule 144A Global Security (CUSIP No.
) with the U.S. Depositary] [[Restricted][Unrestricted] Regulation S Global
Security (CUSIP No.           ) with [Euroclear] [Clearstream]]* in the name of
[insert name of transferor] (the "Transferor").  The Transferor has requested an
                                  ----------
exchange or transfer of such Global Security for an interest in the IAI Global
Security (CUSIP No.           ).

     In connection with such request with respect to a transfer or exchange for
an interest in the IAI Global Security, the Transferor does hereby certify that
such exchange or transfer has been effected in accordance with the transfer
restrictions set forth in the Rule 144A Global Security, the Restricted
Regulation S Global Security and the Unrestricted Regulation S Global Security
(as the case may be) and, with respect to transfers made in reliance on Rule 144
under the Securities Act, certify that the Securities are being transferred in a
transaction permitted by Rule 144 under the Securities Act.

________________
*  Select appropriate depositary.
<PAGE>

     In connection with such request with respect to a transfer or exchange for
an interest in the IAI Global Security, and in respect of such Rule 144A Global
Security, Restricted Regulations S Global Security and Unrestricted Regulation S
Global Security (as the case may be), the Transferor does hereby certify that
such Global Security is being transferred or exchanged in accordance with (i)
the transfer restrictions set forth in the Global Securities and (ii) in
accordance with the Securities Act to a transferee that the Transferor
reasonably believes is purchasing the IAI Global Securities for its own account
or an account with respect to which the transferee exercises sole investment
discretion and the transferee and any such account is an institution that is an
"accredited investor" within the meaning of Rule 501(a)(1), (2), (3) or (7)
under the Securities Act, in each case purchasing IAI Global Securities in a
transaction exempt from the Securities Act and in accordance with any applicable
securities laws of any state of the United States or any other jurisdiction.

     This certificate and the statements contained herein are made for your
benefit and the benefit of the Issuer and the Initial Purchasers.

                                                [Insert Name of Transferor]

                                                By:_____________________________
                                                   Name:
                                                   Title:

Dated:_______________, 2000

cc:  Ameren Energy Generating Company

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