<PAGE>

                                                                     EXHIBIT 4.3

                          LEXICON GENETICS INCORPORATED

                                    INDENTURE

                       DATED AS OF ____________ ____, 200__

                       _____________________________________,

                                   AS TRUSTEE

<PAGE>

                                TABLE OF CONTENTS

<TABLE>
<S>                                                                                               <C>
ARTICLE 1. DEFINITIONS AND INCORPORATION BY REFERENCE.......................................       1

   Section 1.1       Definitions............................................................       1
   Section 1.2       Other Definitions......................................................       4
   Section 1.3       Incorporation by Reference of Trust Indenture Act......................       5
   Section 1.4       Rules of Construction..................................................       5

ARTICLE 2. THE SECURITIES...................................................................       6

   Section 2.1       Issuable in Series.....................................................       6
   Section 2.2       Establishment of Terms of Series of Securities.........................       6
   Section 2.3       Execution and Authentication...........................................       8
   Section 2.4       Registrar and Paying Agent.............................................       9
   Section 2.5       Paying Agent to Hold Money in Trust....................................       9
   Section 2.6       Securityholder Lists..................................................       10
   Section 2.7       Transfer and Exchange.................................................       10
   Section 2.8       Mutilated, Destroyed, Lost and Stolen Securities......................       10
   Section 2.9       Outstanding Securities................................................       11
   Section 2.10      Treasury Securities...................................................       11
   Section 2.11      Temporary Securities..................................................       11
   Section 2.12      Cancellation..........................................................       12
   Section 2.13      Defaulted Interest....................................................       12
   Section 2.14      Global Securities.....................................................       12
   Section 2.15      CUSIP Numbers.........................................................       13

ARTICLE 3. REDEMPTION......................................................................       13

   Section 3.1       Notice to Trustee.....................................................       13
   Section 3.2       Selection of Securities to be Redeemed................................       14
   Section 3.3       Notice of Redemption..................................................       14
   Section 3.4       Effect of Notice of Redemption........................................       14
   Section 3.5       Deposit of Redemption Price...........................................       15
   Section 3.6       Securities Redeemed In Part...........................................       15

ARTICLE 4. COVENANTS.......................................................................       15

   Section 4.1       Payment Of Principal and Interest.....................................       15
   Section 4.2       SEC Reports...........................................................       15
   Section 4.3       Compliance Certificate................................................       15
   Section 4.4       Stay, Extension and Usury Laws........................................       16
   Section 4.5       Corporate Existence...................................................       16
   Section 4.6       Taxes.................................................................       16

ARTICLE 5. SUCCESSORS......................................................................       16

   Section 5.1       When Company May Merge, Etc...........................................       16
   Section 5.2       Successor Corporation Substituted.....................................       16

ARTICLE 6. DEFAULTS AND REMEDIES...........................................................       17

   Section 6.1       Events of Default.....................................................       17
   Section 6.2       Acceleration of Maturity; Rescission and Annulment....................       18
   Section 6.3       Collection of Indebtedness and Suits for Enforcement by Trustee.......       18
</TABLE>

                                        i

<PAGE>

<TABLE>
<S>                                                                                               <C>
   Section 6.4       Trustee May File Proofs of Claim......................................       19
   Section 6.5       Trustee May Enforce Claims Without Possession of Securities...........       20
   Section 6.6       Application of Money Collected........................................       20
   Section 6.7       Limitation on Suits...................................................       20
   Section 6.8       Unconditional Right of Holders to Receive Principal and Interest......       21
   Section 6.9       Restoration of Rights and Remedies....................................       21
   Section 6.10      Rights and Remedies Cumulative........................................       21
   Section 6.11      Delay or Omission Not Waiver..........................................       21
   Section 6.12      Control by Holders....................................................       21
   Section 6.13      Waiver of Past Defaults...............................................       22
   Section 6.14      Undertaking for Costs.................................................       22

ARTICLE 7. TRUSTEE.........................................................................       22

   Section 7.1       Duties of Trustee.....................................................       22
   Section 7.2       Rights of Trustee.....................................................       23
   Section 7.3       Individual Rights of Trustee..........................................       24
   Section 7.4       Trustee's Disclaimer..................................................       25
   Section 7.5       Notice of Defaults....................................................       25
   Section 7.6       Reports by Trustee to Holders.........................................       25
   Section 7.7       Compensation and Indemnity............................................       25
   Section 7.8       Replacement of Trustee................................................       26
   Section 7.9       Successor Trustee by Merger, etc......................................       27
   Section 7.10      Eligibility; Disqualification.........................................       27
   Section 7.11      Preferential Collection of Claims Against Company.....................       27

ARTICLE 8. SATISFACTION AND DISCHARGE; DEFEASANCE..........................................       27

   Section 8.1       Satisfaction and Discharge of Indenture...............................       27
   Section 8.2       Application of Trust Funds; Indemnification...........................       28
   Section 8.3       Legal Defeasance of Securities of Any Series..........................       28
   Section 8.4       Covenant Defeasance...................................................       30
   Section 8.5       Repayment to Company..................................................       31

ARTICLE 9. AMENDMENTS AND WAIVERS..........................................................       31

   Section 9.1       Without Consent of Holders............................................       31
   Section 9.2       With Consent of Holders...............................................       31
   Section 9.3       Limitations...........................................................       32
   Section 9.4       Compliance with Trust Indenture Act...................................       32
   Section 9.5       Revocation and Effect of Consents.....................................       32
   Section 9.6       Notation on or Exchange of Securities.................................       33
   Section 9.7       Trustee Protected.....................................................       33

ARTICLE 10. MISCELLANEOUS..................................................................       33

   Section 10.1      Trust Indenture Act Controls..........................................       33
   Section 10.2      Notices...............................................................       33
   Section 10.3      Communication by Holders with Other Holders...........................       34
   Section 10.4      Certificate and Opinion as to Conditions Precedent....................       34
   Section 10.5      Statements Required in Certificate or Opinion.........................       34
   Section 10.6      Rules by Trustee and Agents...........................................       35
   Section 10.7      Legal Holidays........................................................       35
   Section 10.8      No Recourse Against Others............................................       35
   Section 10.9      Counterparts..........................................................       35
</TABLE>

                                       ii
<PAGE>

<TABLE>
<S>                                                                                               <C>
   Section 10.10      Governing Laws.......................................................       35
   Section 10.11      No Adverse Interpretation Of Other Agreements........................       35
   Section 10.12      Successors...........................................................       35
   Section 10.13      Severability.........................................................       36
   Section 10.14      Table of Contents, Headings, Etc.....................................       36
   Section 10.15      Securities in a Foreign Currency or in ECU...........................       36
   Section 10.16      Judgment Currency....................................................       36

ARTICLE 11. SINKING FUNDS..................................................................       37

   Section 11.1      Applicability Of Article..............................................       37
   Section 11.2      Satisfaction of Sinking Fund Payments with Securities.................       37
   Section 11.3      Redemption of Securities for Sinking Fund.............................       38
</TABLE>

                                       iii
<PAGE>

                          LEXICON GENETICS INCORPORATED
         RECONCILIATION AND TIE BETWEEN TRUST INDENTURE ACT OF 1939 AND
                   INDENTURE, DATED AS OF __________ __, 200_

<TABLE>
<S>                                                                         <C>
Section      310(a)(1).........................................                       7.10
                (a)(2).........................................                       7.10
                (a)(3).........................................             NOT APPLICABLE
                (a)(4).........................................             NOT APPLICABLE
                (a)(5).........................................                       7.10
                   (b).........................................                       7.10
Section         311(a).........................................                       7.11
                   (b).........................................                       7.11
                   (c).........................................             NOT APPLICABLE
Section         312(a).........................................                        2.6
                   (b).........................................                       10.3
                   (c).........................................                       10.3
Section         313(a).........................................                        7.6
                (b)(1).........................................                        7.6
                (b)(2).........................................                        7.6
                (c)(1).........................................                        7.6
                   (d).........................................                        7.6
Section         314(a).........................................                  4.2, 10.5
                   (b).........................................             NOT APPLICABLE
                (c)(1).........................................                       10.4
                (c)(2).........................................                       10.4
                (c)(3).........................................             NOT APPLICABLE
                   (d).........................................             NOT APPLICABLE
                   (e).........................................                       10.5
                   (f).........................................             NOT APPLICABLE
Section         315(a).........................................                        7.1
                   (b).........................................                        7.5
                   (c).........................................                        7.1
                   (d).........................................                        7.1
                   (e).........................................                       6.14
Section         316(a).........................................                       2.10
             (a)(1)(a).........................................                       6.12
             (a)(1)(b).........................................                       6.13
                   (b).........................................                        6.8
Section      317(a)(1).........................................                        6.3
                (a)(2).........................................                        6.4
                   (b).........................................                        2.5
Section         318(a).........................................                       10.1
</TABLE>

Note: This reconciliation and tie shall not, for any purpose, be deemed to be
part of the Indenture.

                                       iv
<PAGE>

      Indenture dated as of _______ ___, 200__ between Lexicon Genetics
Incorporated, a Delaware corporation ("Company"), and _________________________,
as trustee ("Trustee").

      Each party agrees as follows for the benefit of the other party and for
the equal and ratable benefit of the Holders of the Securities issued under this
Indenture.

                                   ARTICLE 1.
                   DEFINITIONS AND INCORPORATION BY REFERENCE

SECTION 1.1 DEFINITIONS.

      "Additional Amounts" means any additional amounts which are required
hereby or by any Security, under circumstances specified herein or therein, to
be paid by the Company in respect of certain taxes imposed on Holders specified
herein or therein and which are owing to such Holders.

      "Affiliate" of any specified person means any other person directly or
indirectly controlling or controlled by or under direct or indirect common
control with such specified person. For the purposes of this definition,
"control" (including, with correlative meanings, the terms "controlled by" and
"under common control with"), as used with respect to any person, shall mean the
possession, directly or indirectly, of the power to direct or cause the
direction of the management or policies of such person, whether through the
ownership of voting securities or by agreement or otherwise.

      "Agent" means any Registrar, Paying Agent or Service Agent.

      "Authorized Newspaper" means a newspaper in an official language of the
country of publication customarily published at least once a day for at least
five days in each calendar week and of general circulation in the place in
connection with which the term is used. If it shall be impractical in the
opinion of the Trustee to make any publication of any notice required hereby in
an Authorized Newspaper, any publication or other notice in lieu thereof that is
made or given by the Trustee shall constitute a sufficient publication of such
notice.

      "Bearer" means anyone in possession from time to time of a Bearer
Security.

      "Bearer Security" means any Security, including any interest coupon
appertaining thereto, that does not provide for the identification of the Holder
thereof.

      "Board of Directors" means the Board of Directors of the Company or any
duly authorized committee thereof.

      "Board Resolution" means a copy of a resolution certified by the Secretary
or an Assistant Secretary of the Company to have been adopted by the Board of
Directors or pursuant to authorization by the Board of Directors and to be in
full force and effect on the date of the certificate and delivered to the
Trustee.

      "Business Day" means, unless otherwise provided by Board Resolution,
Officers' Certificate or supplemental indenture hereto for a particular Series,
any day except a Saturday, Sunday or a legal holiday in The City of New York on
which banking institutions are authorized or required by law, regulation or
executive order to close.

<PAGE>

      "Capital Stock" means any and all shares, interests, participations,
rights or other equivalents (however designated) of corporate stock.

      "Company" means the party named as such above until a successor replaces
it and thereafter means the successor.

      "Company Order" means a written order signed in the name of the Company by
two Officers, one of whom must be the Company's principal executive officer,
principal financial officer or principal accounting officer.

      "Company Request" means a written request signed in the name of the
Company by its Chief Executive Officer, the President or a Vice President, and
by its Treasurer, an Assistant Treasurer, its Secretary or an Assistant
Secretary, and delivered to the Trustee.

      "Corporate Trust Office" means the office of the Trustee at which at any
particular time its corporate trust business shall be principally administered.

      "Default" means any event which is, or after notice or passage of time or
both would be, an Event of Default.

      "Depository" means, with respect to the Securities of any Series issuable
or issued in whole or in part in the form of one or more Global Securities, the
person designated as Depository for such Series by the Company, which Depository
shall be a clearing agency registered under the Exchange Act; and if at any time
there is more than one such person, "Depository" as used with respect to the
Securities of any Series shall mean the Depository with respect to the
Securities of such Series.

      "Discount Security" means any Security that provides for an amount less
than the stated principal amount thereof to be due and payable upon declaration
of acceleration of the maturity thereof pursuant to Section 6.2.

      "Dollars" and "$" means the currency of The United States of America.

      "ECU" means the European Currency Unit as determined by the Commission of
the European Union.

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

      "Foreign Currency" means any currency or currency unit issued by a
government other than the government of The United States of America.

      "Foreign Government Obligations" means, with respect to Securities of any
Series that are denominated in a Foreign Currency, (i) direct obligations of the
government that issued or caused to be issued such currency for the payment of
which obligations its full faith and credit is pledged or (ii) obligations of a
person controlled or supervised by or acting as an agency or instrumentality of
such government the timely payment of which is unconditionally guaranteed as a
full faith and credit obligation by such government, which, in either case under
clauses (i) or (ii), are not callable or redeemable at the option of the issuer
thereof.

      "GAAP" means generally accepted accounting principles 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

                                       2
<PAGE>

other entity as have been approved by a significant segment of the accounting
profession, which are in effect as of the date of determination.

      "Global Security" or "Global Securities" means a Security or Securities,
as the case may be, in the form established pursuant to Section 2.2 evidencing
all or part of a Series of Securities, issued to the Depository for such Series
or its nominee, and registered in the name of such Depository or nominee.

      "Holder" or "Securityholder" means a person in whose name a Security is
registered or the holder of a Bearer Security.

      "Indenture" means this Indenture as amended or supplemented, from time to
time and shall include the form and terms of particular Series of Securities
established as contemplated hereunder.

      "interest," with respect to any Discount Security which by its terms bears
interest only after Maturity, means interest payable after Maturity.

      "Maturity," when used with respect to any Security or installment of
principal thereof, means the date on which the principal of such Security or
such installment of principal becomes due and payable as therein or herein
provided, whether at the Stated Maturity or by declaration of acceleration, call
for redemption or otherwise.

      "Officer" means the Chief Executive Officer, the President, any
Vice-President, the Treasurer, the Secretary, any Assistant Treasurer or any
Assistant Secretary of the Company.

      "Officers' Certificate" means a certificate signed by two Officers, one of
whom must be the Company's principal executive officer, principal financial
officer or principal accounting officer.

      "Opinion of Counsel" means a written opinion of legal counsel who is
acceptable to the Trustee. The counsel may be an employee of or counsel to the
Company.

      "person" means any individual, corporation, partnership, joint venture,
association, limited liability company, joint-stock company, trust,
unincorporated organization or government or any agency or political subdivision
thereof.

      "principal" of a Security means the principal of the Security plus, when
appropriate, the premium, if any, on, and any Additional Amounts in respect of,
the Security.

      "Responsible Officer" means any officer of the Trustee in its Corporate
Trust Office with direct responsibility for the administration of this Indenture
and also means, with respect to a particular corporate trust matter, any other
officer to whom any corporate trust matter is referred because of his or her
knowledge of and familiarity with a particular subject.

      "SEC" means the Securities and Exchange Commission.

      "Securities" means the debentures, notes or other debt instruments of the
Company of any Series authenticated and delivered under this Indenture.

      "Series" or "Series of Securities" means each series of debentures, notes
or other debt instruments of the Company created pursuant to Sections 2.1 and
2.2 hereof.

                                       3
<PAGE>

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

      "Subsidiary" of any specified person means any corporation, association or
other business entity of which more than 50% of the total voting power of shares
of Capital Stock entitled (without regard to the occurrence of any contingency)
to vote in the election of directors, managers or trustees thereof is at the
time owned or controlled, directly or indirectly, by such person or one or more
of the other Subsidiaries of that person or a combination thereof.

      "TIA" means the Trust Indenture Act of 1939 (15 U.S. Code Sections
77aaa-77bbbb) as in effect on the date of this Indenture; provided, however,
that in the event the Trust Indenture Act of 1939 is amended after such date,
"TIA" means, to the extent required by any such amendment, the Trust Indenture
Act as so amended.

      "Trustee" means the person named as the "Trustee" in the first paragraph
of this instrument until a successor Trustee shall have become such pursuant to
the applicable provisions of this Indenture, and thereafter "Trustee" shall mean
each person who is then a Trustee hereunder, and if at any time there is more
than one such person, "Trustee" as used with respect to the Securities of any
Series shall mean the Trustee with respect to Securities of that Series.

      "U.S. Government Obligations" means securities which are (i) direct
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, and which in the case of both
(i) and (ii) 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 as
custodian with respect to any such U.S. Government Obligation 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 evidenced by such depository receipt.

SECTION 1.2 OTHER DEFINITIONS.

<TABLE>
<CAPTION>
Term                                                                         Defined in Section
----                                                                         ------------------
<S>                                                                          <C>
"Bankruptcy Law"......................................................                 6.1
"Custodian"...........................................................                 6.1
"Event of Default"....................................................                 6.1
"Journal".............................................................               10.15
"Judgment Currency"...................................................               10.16
"Legal Holiday".......................................................                10.7
"mandatory sinking fund payment"......................................                11.1
"Market Exchange Rate"................................................               10.15
"New York Banking Day"................................................               10.16
"optional sinking fund payment".......................................                11.1
"Paying Agent"........................................................                 2.4
"Registrar"...........................................................                 2.4
"Required Currency"...................................................               10.16
</TABLE>

                                       4
<PAGE>

<TABLE>
<S>                                                                            <C>
"Service Agent".......................................................         2.4
"successor person"....................................................         5.1
</TABLE>

SECTION 1.3 INCORPORATION BY REFERENCE OF TRUST INDENTURE ACT.

      Whenever this Indenture refers to a provision of the TIA, the provision is
incorporated by reference in and made a part of this Indenture. The following
TIA terms used in this Indenture have the following meanings:

      "Commission" means the SEC.

      "indenture securities" means the Securities.

      "indenture security holder" means a Securityholder.

      "indenture to be qualified" means this Indenture.

      "indenture trustee" or "institutional trustee" means the Trustee.

      "obligor" on the indenture securities means the Company and any successor
obligor upon the Securities.

      All other terms used in this Indenture that are defined by the TIA,
defined by TIA reference to another statute or defined by SEC rule under the TIA
and not otherwise defined herein are used herein as so defined.

SECTION 1.4 RULES OF CONSTRUCTION.

      Unless the context otherwise requires:

            (a) a term has the meaning assigned to it;

            (b) an accounting term not otherwise defined has the meaning
      assigned to it in accordance with generally accepted accounting
      principles;

            (c) references to "generally accepted accounting principles" and
      "GAAP" shall mean generally accepted accounting principles in effect as of
      the time when and for the period as to which such accounting principles
      are to be applied;

            (d) "or" is not exclusive;

            (e) words in the singular include the plural, and in the plural
      include the singular; and

            (f) provisions apply to successive events and transactions.

                                       5
<PAGE>

                                   ARTICLE 2.
                                 THE SECURITIES

SECTION 2.1 ISSUABLE IN SERIES.

      The aggregate principal amount of Securities that may be authenticated and
delivered under this Indenture is unlimited. The Securities may be issued in one
or more Series. All Securities of a Series shall be identical except as may be
set forth or determined in the manner provided in a Board Resolution,
supplemental indenture or Officers' Certificate detailing the adoption of the
terms thereof pursuant to authority granted under a Board Resolution. In the
case of Securities of a Series to be issued from time to time, the Board
Resolution, Officers' Certificate or supplemental indenture detailing the
adoption of the terms thereof pursuant to authority granted under a Board
Resolution may provide for the method by which specified terms (such as interest
rate, maturity date, record date or date from which interest shall accrue) are
to be determined. Securities may differ between Series in respect of any
matters, provided that all Series of Securities shall be equally and ratably
entitled to the benefits of the Indenture.

SECTION 2.2 ESTABLISHMENT OF TERMS OF SERIES OF SECURITIES.

      At or prior to the issuance of any Securities within a Series, the
following shall be established (as to the Series generally, in the case of
Subsection 2.2.1 and either as to such Securities within the Series or as to the
Series generally in the case of Subsections 2.2.2 through 2.2.23) by or pursuant
to a Board Resolution, and set forth or determined in the manner provided in a
Board Resolution, supplemental indenture or an Officers' Certificate:

            2.2.1 the title of the Series (which shall distinguish the
      Securities of that particular Series from the Securities of any other
      Series);

            2.2.2 the price or prices (expressed as a percentage of the
      principal amount thereof) at which the Securities of the Series will be
      issued;

            2.2.3 any limit upon the aggregate principal amount of the
      Securities of the Series which 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 the Series pursuant to Section 2.7, 2.8, 2.11, 3.6 or 9.6);

            2.2.4 the date or dates on which the principal of the Securities of
      the Series is payable;

            2.2.5 the rate or rates (which may be fixed or variable) per annum
      or, if applicable, the method used to determine such rate or rates
      (including, but not limited to, any commodity, commodity index, stock
      exchange index or financial index) at which the Securities of the Series
      shall bear interest, if any, the date or dates from which such interest,
      if any, shall accrue, the date or dates on which such interest, if any,
      shall commence and be payable and any regular record date for the interest
      payable on any interest payment date;

            2.2.6 the place or places where the principal of and interest, if
      any, on the Securities of the Series shall be payable, where the
      Securities of such Series may be surrendered for registration of transfer
      or exchange and where notices and demands to or upon the Company in
      respect of the Securities of such Series and this Indenture may be served,
      and the method of such payment, if by wire transfer, mail or other means;

                                       6
<PAGE>

            2.2.7 if applicable, the period or periods within which, the price
      or prices at which and the terms and conditions upon which the Securities
      of the Series may be redeemed, in whole or in part, at the option of the
      Company;

            2.2.8 the obligation, if any, of the Company to redeem or purchase
      the Securities of the Series pursuant to any sinking fund or analogous
      provisions or at the option of a Holder thereof and the period or periods
      within which, the price or prices at which and the terms and conditions
      upon which Securities of the Series shall be redeemed or purchased, in
      whole or in part, pursuant to such obligation;

            2.2.9 the dates, if any, on which and the price or prices at which
      the Securities of the Series will be repurchased by the Company at the
      option of the Holders thereof and other detailed terms and provisions of
      such repurchase obligations;

            2.2.10 if other than denominations of $1,000 and any integral
      multiple thereof, the denominations in which the Securities of the Series
      shall be issuable;

            2.2.11 the forms of the Securities of the Series in bearer or fully
      registered form (and, if in fully registered form, whether the Securities
      will be issuable as Global Securities);

            2.2.12 if other than the principal amount thereof, the portion of
      the principal amount of the Securities of the Series that shall be payable
      upon declaration of acceleration of the maturity thereof pursuant to
      Section 6.2;

            2.2.13 the currency of denomination of the Securities of the Series,
      which may be Dollars or any Foreign Currency, including, but not limited
      to, the ECU, and if such currency of denomination is a composite currency
      other than the ECU, the agency or organization, if any, responsible for
      overseeing such composite currency;

            2.2.14 the designation of the currency, currencies or currency units
      in which payment of the principal of and interest, if any, on the
      Securities of the Series will be made;

            2.2.15 if payments of principal of or interest, if any, on the
      Securities of the Series are to be made in one or more currencies or
      currency units other than that or those in which such Securities are
      denominated, the manner in which the exchange rate with respect to such
      payments will be determined;

            2.2.16 the manner in which the amounts of payment of principal of or
      interest, if any, on the Securities of the Series will be determined, if
      such amounts may be determined by reference to an index based on a
      currency or currencies or by reference to a commodity, commodity index,
      stock exchange index or financial index;

            2.2.17 the provisions, if any, relating to any security provided for
      the Securities of the Series;

            2.2.18 any addition to or change in the Events of Default which
      applies to any Securities of the Series and any change in the right of the
      Trustee or the requisite Holders of such Securities to declare the
      principal amount thereof due and payable pursuant to Section 6.2;

            2.2.19 any addition to or change in the covenants set forth in
      Articles IV or V which applies to Securities of the Series;

                                       7
<PAGE>

            2.2.20 the provisions, if any, relating to conversion of any
      Securities of such Series, including, if applicable, the conversion price,
      the conversion period, provisions as to whether conversion will be
      mandatory, at the option of the Holders or at the option of the Company,
      the events requiring an adjustment of the conversion price and provisions
      affecting conversion if such Series of Securities are redeemed;

            2.2.21 whether the Securities of such Series will be senior debt
      securities or subordinated debt securities and, if applicable, a
      description of the subordination terms thereof;

            2.2.22 any depositories, interest rate calculation agents, exchange
      rate calculation agents or other agents with respect to Securities of such
      Series if other than those appointed herein; and

            2.2.23 any other terms of the Securities of the Series (which may
      modify or delete any provision of this Indenture insofar as it applies to
      such Series).

      All Securities of any one Series need not be issued at the same time and
may be issued from time to time, consistent with the terms of this Indenture, if
so provided by or pursuant to the Board Resolution, supplemental indenture
hereto or Officers' Certificate referred to above, and the authorized principal
amount of any Series may not be increased to provide for issuances of additional
Securities of such Series, unless otherwise provided in such Board Resolution,
supplemental indenture or Officers' Certificate.

SECTION 2.3 EXECUTION AND AUTHENTICATION.

      Two Officers shall sign the Securities for the Company by manual or
facsimile signature.

      If an Officer whose signature is on a Security no longer holds that office
at the time the Security is authenticated, the Security shall nevertheless be
valid.

      A Security shall not be valid until authenticated by the manual signature
of the Trustee or an authenticating agent. The signature shall be conclusive
evidence that the Security has been authenticated under this Indenture.

      The Trustee shall at any time, and from time to time, authenticate
Securities for original issue in the principal amount provided in the Board
Resolution, supplemental indenture hereto or Officers' Certificate, upon receipt
by the Trustee of a Company Order. Such Company Order may authorize
authentication and delivery pursuant to oral or electronic instructions from the
Company or its duly authorized agent or agents, which oral instructions shall be
promptly confirmed in writing. Each Security shall be dated the date of its
authentication unless otherwise provided by a Board Resolution, a supplemental
indenture hereto or an Officers' Certificate.

      The aggregate principal amount of Securities of any Series outstanding at
any time may not exceed any limit upon the maximum principal amount for such
Series set forth in the Board Resolution, supplemental indenture hereto or
Officers' Certificate delivered pursuant to Section 2.2, except as provided in
Section 2.8.

      Prior to the issuance of Securities of any Series, the Trustee shall have
received and (subject to Section 7.2) shall be fully protected in relying on:
(a) the Board Resolution, supplemental indenture hereto or Officers' Certificate
establishing the form of the Securities of that Series or of Securities within
that Series and the terms of the Securities of that Series or of Securities
within that Series, (b) an Officers' Certificate complying with Section 10.4 and
(c) an Opinion of Counsel complying with Section 10.4.

                                       8
<PAGE>

      The Trustee shall have the right to decline to authenticate and deliver
any Securities of such Series: (a) if the Trustee, being advised by counsel,
determines that such action may not be taken lawfully; or (b) if the Trustee in
good faith by its board of directors or trustees, executive committee or a trust
committee of directors and/or vice-presidents shall determine that such action
would expose the Trustee to personal liability to Holders of any then
outstanding Series of Securities.

      The Trustee may appoint an authenticating agent acceptable to the Company
to authenticate Securities. An authenticating agent may authenticate Securities
whenever the Trustee may do so. Each reference in this Indenture to
authentication by the Trustee includes authentication by such agent. An
authenticating agent has the same rights as an Agent to deal with the Company or
an Affiliate of the Company.

SECTION 2.4 REGISTRAR AND PAYING AGENT.

      The Company shall maintain, with respect to each Series of Securities, at
the place or places specified with respect to such Series pursuant to Section
2.2, an office or agency where Securities of such Series may be presented or
surrendered for payment ("Paying Agent"), where Securities of such Series may be
surrendered for registration of transfer or exchange ("Registrar") and where
notices and demands to or upon the Company in respect of the Securities of such
Series and this Indenture may be served ("Service Agent"). The Registrar shall
keep a register with respect to each Series of Securities and to their transfer
and exchange. The Company will give prompt written notice to the Trustee of the
name and address, and any change in the name or address, of each Registrar,
Paying Agent or Service Agent. If at any time the Company shall fail to maintain
any such required Registrar, Paying Agent or Service Agent or shall fail to
furnish the Trustee with the name and address thereof, such presentations,
surrenders, notices and demands may be made or served at the Corporate Trust
Office of the Trustee, and the Company hereby appoints the Trustee as its agent
to receive all such presentations, surrenders, notices and demands.

      The Company may also from time to time designate one or more
co-registrars, additional paying agents or additional service agents and may
from time to time rescind such designations; provided, however, that no such
designation or rescission shall in any manner relieve the Company of its
obligations to maintain a Registrar, Paying Agent and Service Agent in each
place so specified pursuant to Section 2.2 for Securities of any Series for such
purposes. The Company will give prompt written notice to the Trustee of any such
designation or rescission and of any change in the name or address of any such
co-registrar, additional paying agent or additional service agent. The term
"Registrar" includes any co-registrar; the term "Paying Agent" includes any
additional paying agent; and the term "Service Agent" includes any additional
service agent.

      The Company hereby appoints the Trustee as the initial Registrar, Paying
Agent and Service Agent for each Series unless another Registrar, Paying Agent
or Service Agent, as the case may be, is appointed prior to the time Securities
of that Series are first issued.

SECTION 2.5 PAYING AGENT TO HOLD MONEY IN TRUST.

      The Company shall require each Paying Agent other than the Trustee to
agree in writing that the Paying Agent will hold in trust, for the benefit of
Securityholders of any Series of Securities, or the Trustee, all money held by
the Paying Agent for the payment of principal of or interest on the Series of
Securities, and will notify the Trustee of any default by the Company in making
any such payment. While any such default continues, the Trustee may require a
Paying Agent to pay all money held by it to the Trustee. The Company at any time
may require a Paying Agent to pay all money held by it to the Trustee. Upon
payment over to the Trustee, the Paying Agent (if other than the Company or a
Subsidiary of the

                                       9
<PAGE>

Company) shall have no further liability for the money. If the Company or a
Subsidiary of the Company acts as Paying Agent, it shall segregate and hold in a
separate trust fund for the benefit of Securityholders of any Series of
Securities all money held by it as Paying Agent.

SECTION 2.6 SECURITYHOLDER LISTS.

      The Trustee shall preserve in as current a form as is reasonably
practicable the most recent list available to it of the names and addresses of
Securityholders of each Series of Securities and shall otherwise comply with TIA
Section 312(a). If the Trustee is not the Registrar, the Company shall furnish
to the Trustee at least ten (10) days before each interest payment date and at
such other times as the Trustee may request in writing a list, in such form and
as of such date as the Trustee may reasonably require, of the names and
addresses of Securityholders of each Series of Securities.

SECTION 2.7 TRANSFER AND EXCHANGE.

      Where Securities of a Series are presented to the Registrar or a
co-registrar with a request to register a transfer or to exchange them for an
equal principal amount of Securities of the same Series, the Registrar shall
register the transfer or make the exchange if its requirements for such
transactions are met. To permit registrations of transfers and exchanges, the
Trustee shall authenticate Securities at the Registrar's request. No service
charge shall be made for any registration of transfer or exchange (except as
otherwise expressly permitted herein), but the Company may require payment of a
sum sufficient to cover any transfer tax or similar governmental charge payable
in connection therewith (other than any such transfer tax or similar
governmental charge payable upon exchanges pursuant to Sections 2.11, 3.6 or
9.6).

      Neither the Company nor the Registrar shall be required (a) to issue,
register the transfer of, or exchange Securities of any Series for the period
beginning at the opening of business fifteen days immediately preceding the
mailing of a notice of redemption of Securities of that Series selected for
redemption and ending at the close of business on the day of such mailing, or
(b) to register the transfer of or exchange Securities of any Series selected,
called or being called for redemption as a whole or the portion being redeemed
of any such Securities selected, called or being called for redemption in part.

SECTION 2.8 MUTILATED, DESTROYED, LOST AND STOLEN SECURITIES.

      If any mutilated Security is surrendered to the Trustee, the Company shall
execute and the Trustee shall authenticate and make available for delivery in
exchange therefor a new Security of the same Series and of like tenor and
principal amount and bearing a number not contemporaneously outstanding.

      If there shall be delivered to the Company and the Trustee (i) evidence to
their satisfaction of the destruction, loss or theft of any Security and (ii)
such security or indemnity as may be required by them to save each of them and
any agent of either of them harmless, then, in the absence of notice to the
Company or the Trustee that such Security has been acquired by a bona fide
purchaser, the Company shall execute and upon its request the Trustee shall
authenticate and make available for delivery, in lieu of any such destroyed,
lost or stolen Security, a new Security of the same Series and of like tenor and
principal amount and bearing a number not contemporaneously outstanding.

      In case any such mutilated, destroyed, lost or stolen Security has become
or is about to become due and payable, the Company in its discretion may,
instead of issuing a new Security, pay such Security.

                                       10
<PAGE>

      Upon the issuance of any new Security under this Section, the Company may
require the payment of a sum sufficient to cover any tax or other governmental
charge that may be imposed in relation thereto and any other expenses (including
the fees and expenses of the Trustee) connected therewith.

      Every new Security of any Series issued pursuant to this Section in lieu
of any destroyed, lost or stolen Security shall constitute an original
additional contractual obligation of the Company, whether or not the destroyed,
lost or stolen Security shall be at any time enforceable by anyone, and shall be
entitled to all the benefits of this Indenture equally and proportionately with
any and all other Securities of that Series duly issued hereunder.

      The provisions of this Section are exclusive and shall preclude (to the
extent lawful) all other rights and remedies with respect to the replacement or
payment of mutilated, destroyed, lost or stolen Securities.

SECTION 2.9 OUTSTANDING SECURITIES.

      The Securities outstanding at any time are all the Securities
authenticated by the Trustee except for those canceled by it, those delivered to
it for cancellation, those reductions in the interest on a Global Security
effected by the Trustee in accordance with the provisions hereof and those
described in this Section as not outstanding.

      If a Security is replaced pursuant to Section 2.8, it ceases to be
outstanding until the Trustee receives proof satisfactory to it that the
replaced Security is held by a bona fide purchaser.

      If the Paying Agent (other than the Company, a Subsidiary of the Company
or an Affiliate of the Company) holds on the Maturity of Securities of a Series
money sufficient to pay such Securities payable on that date, then on and after
that date such Securities of the Series cease to be outstanding and interest on
them ceases to accrue.

      A Security does not cease to be outstanding because the Company or an
Affiliate of the Company holds the Security.

      In determining whether the Holders of the requisite principal amount of
outstanding Securities have given any request, demand, authorization, direction,
notice, consent or waiver hereunder, the principal amount of a Discount Security
that shall be deemed to be outstanding for such purposes shall be the amount of
the principal thereof that would be due and payable as of the date of such
determination upon a declaration of acceleration of the Maturity thereof
pursuant to Section 6.2.

SECTION 2.10 TREASURY SECURITIES.

      In determining whether the Holders of the required principal amount of
Securities of a Series have concurred in any request, demand, authorization,
direction, notice, consent or waiver, Securities of a Series owned by the
Company shall be disregarded, except that for the purposes of determining
whether the Trustee shall be protected in relying on any such request, demand,
authorization, direction, notice, consent or waiver, only Securities of a Series
that the Trustee knows are so owned shall be so disregarded.

SECTION 2.11 TEMPORARY SECURITIES.

      Until definitive Securities are ready for delivery, the Company may
prepare and the Trustee shall authenticate temporary Securities upon a Company
Order. Temporary Securities shall be substantially in the form of definitive
Securities but may have variations that the Company considers appropriate for

                                       11
<PAGE>

temporary Securities. Without unreasonable delay, the Company shall prepare and
the Trustee upon request shall authenticate definitive Securities of the same
Series and date of maturity in exchange for temporary Securities. Until so
exchanged, temporary securities shall have the same rights under this Indenture
as the definitive Securities.

SECTION 2.12 CANCELLATION.

      The Company at any time may deliver Securities to the Trustee for
cancellation. The Registrar and the Paying Agent shall forward to the Trustee
any Securities surrendered to them for registration of transfer, exchange or
payment. The Trustee shall cancel all Securities surrendered for registration of
transfer, exchange, payment, replacement or cancellation and deliver such
canceled Securities to the Company, unless the Company otherwise directs;
provided that the Trustee shall not be required to destroy Securities. The
Company may not issue new Securities to replace Securities that it has paid or
delivered to the Trustee for cancellation.

SECTION 2.13 DEFAULTED INTEREST.

      If the Company defaults in a payment of interest on a Series of
Securities, it shall pay the defaulted interest, plus, to the extent permitted
by law, any interest payable on the defaulted interest, to the persons who are
Securityholders of the Series on a subsequent special record date. The Company
shall fix the record date and payment date. At least ten (10) days before the
record date, the Company shall mail to the Trustee and to each Securityholder of
the Series a notice that states the record date, the payment date and the amount
of interest to be paid. The Company may pay defaulted interest in any other
lawful manner.

SECTION 2.14 GLOBAL SECURITIES.

            2.14.1 Terms of Securities. A Board Resolution, a supplemental
      indenture hereto or an Officers' Certificate shall establish whether the
      Securities of a Series shall be issued in whole or in part in the form of
      one or more Global Securities and the Depository for such Global Security
      or Securities.

            2.14.2 Transfer and Exchange. Notwithstanding any provisions to the
      contrary contained in Section 2.7 of the Indenture and in addition
      thereto, any Global Security shall be exchangeable pursuant to Section 2.7
      of the Indenture for Securities registered in the names of Holders other
      than the Depository for such Security or its nominee only if (i) such
      Depository notifies the Company that it is unwilling or unable to continue
      as Depository for such Global Security or if at any time such Depository
      ceases to be a clearing agency registered under the Exchange Act, and, in
      either case, the Company fails to appoint a successor Depository
      registered as a clearing agency under the Exchange Act within 90 days of
      such event, (ii) the Company executes and delivers to the Trustee an
      Officers' Certificate to the effect that such Global Security shall be so
      exchangeable or (iii) an Event of Default with respect to The Securities
      represented by such Global Security shall have happened and be continuing.
      Any Global Security that is exchangeable pursuant to the preceding
      sentence shall be exchangeable for Securities registered in such names as
      the Depository shall direct in writing in an aggregate principal amount
      equal to the principal amount of the Global Security with like tenor and
      terms.

      Except as provided in this Section 2.14.2, a Global Security may not be
transferred except as a whole by the Depository with respect to such Global
Security to a nominee of such Depository, by a nominee of such Depository to
such Depository or another nominee of such Depository or by the Depository or
any such nominee to a successor Depository or a nominee of such a successor
Depository.

                                       12
<PAGE>

            2.14.3 Legend. Any Global Security issued hereunder shall bear a
      legend in substantially the following form:

      "This Security is a Global Security within the meaning of the Indenture
hereinafter referred to and is registered in the name of the Depository or a
nominee of the Depository. This Security is exchangeable for Securities
registered in the name of a person other than the Depository or its nominee only
in the limited circumstances described in the Indenture, and may not be
transferred except as a whole by the Depository to a nominee of the Depository,
by a nominee of the Depository to the Depository or another nominee of the
Depository or by the Depository or any such nominee to a successor Depository or
a nominee of such a successor Depository."

            2.14.4 Acts of Holders. The Depository, as a Holder, may appoint
      agents and otherwise authorize participants to give or take any request,
      demand, authorization, direction, notice, consent, waiver or other action
      which a Holder is entitled to give or take under the Indenture.

            2.14.5 Payments. Notwithstanding the other provisions of this
      Indenture, unless otherwise specified as contemplated by Section 2.2,
      payment of the principal of and interest, if any, on any Global Security
      shall be made to the Holder thereof.

            2.14.6 Consents, Declaration and Directions. Except as provided in
      Section 2.14.5, the Company, the Trustee and any Agent shall treat a
      person as the Holder of such principal amount of outstanding Securities of
      such Series represented by a Global Security as shall be specified in a
      written statement of the Depository with respect to such Global Security,
      for purposes of obtaining any consents, declarations, waivers or
      directions required to be given by the Holders pursuant to this Indenture.

SECTION 2.15 CUSIP NUMBERS.

      The Company in issuing the Securities may use "CUSIP" numbers (if then
generally in use), and, if so, the Trustee shall use "CUSIP" numbers in notices
of redemption as a convenience to Holders; provided that any such notice may
state that no representation is made as to the correctness of such numbers
either as printed on the Securities or as contained in any notice of a
redemption and that reliance may be placed only on the other elements of
identification printed on the Securities, and any such redemption shall not be
affected by any defect in or omission of such numbers.

                                   ARTICLE 3.
                                   REDEMPTION

SECTION 3.1 NOTICE TO TRUSTEE.

      The Company may, with respect to any Series of Securities, reserve the
right to redeem and pay the Series of Securities or may covenant to redeem and
pay the Series of Securities or any part thereof prior to the Stated Maturity
thereof at such time and on such terms as provided for in such Securities. If a
Series of Securities is redeemable and the Company wants or is obligated to
redeem prior to the Stated Maturity thereof all or part of the Series of
Securities pursuant to the terms of such Securities, it shall notify the Trustee
of the redemption date and the principal amount of Series of Securities to be
redeemed. The Company shall give the notice at least 40 days before the
redemption date (or such shorter notice as may be acceptable to the Trustee).

                                       13
<PAGE>

SECTION 3.2 SELECTION OF SECURITIES TO BE REDEEMED.

      Unless otherwise indicated for a particular Series by a Board Resolution,
a supplemental indenture or an Officers' Certificate, if less than all the
Securities of a Series are to be redeemed, the Trustee shall select the
Securities of the Series to be redeemed in any manner that the Trustee deems
fair and appropriate. The Trustee shall make the selection from Securities of
the Series outstanding not previously called for redemption. The Trustee may
select for redemption portions of the principal of Securities of the Series that
have denominations larger than $1,000. Securities of the Series and portions of
them it selects shall be in amounts of $1,000 or whole multiples of $1,000 or,
with respect to Securities of any Series issuable in other denominations
pursuant to Section 2.2.10, the minimum principal denomination for each Series
and integral multiples thereof. Provisions of this Indenture that apply to
Securities of a Series called for redemption also apply to portions of
Securities of that Series called for redemption.

SECTION 3.3 NOTICE OF REDEMPTION.

      Unless otherwise indicated for a particular Series by Board Resolution, a
supplemental indenture hereto or an Officers' Certificate, at least 30 days but
not more than 60 days before a redemption date, the Company shall mail a notice
of redemption by first-class mail to each Holder whose Securities are to be
redeemed and, if any Bearer Securities are outstanding, publish on one occasion
a notice in an Authorized Newspaper.

      The notice shall identify the Securities of the Series to be redeemed and
shall state:

            (a) the redemption date;

            (b) the redemption price;

            (c) the name and address of the Paying Agent;

            (d) that Securities of the Series called for redemption must be
      surrendered to the Paying Agent to collect the redemption price;

            (e) that interest on Securities of the Series called for redemption
      ceases to accrue on and after the redemption date;

            (f) the CUSIP number, if any; and

            (g) any other information as may be required by the terms of the
      particular Series or the Securities of a Series being redeemed.

      At the Company's request, the Trustee shall give the notice of redemption
in the Company's name and at its expense.

SECTION 3.4 EFFECT OF NOTICE OF REDEMPTION.

      Once notice of redemption is mailed or published as provided in Section
3.3, Securities of a Series called for redemption become due and payable on the
redemption date and at the redemption price. A notice of redemption may not be
conditional. Upon surrender to the Paying Agent, such Securities shall be paid
at the redemption price plus accrued interest to the redemption date; provided
that installments of interest whose Stated Maturity is on or prior to the
redemption date shall be payable to the Holders of

                                       14
<PAGE>

such Securities (or one or more predecessor Securities) registered at the close
of business on the relevant record date therefor according to their terms and
the terms of this Indenture.

SECTION 3.5 DEPOSIT OF REDEMPTION PRICE.

      On or before 10:00 a.m., New York City time, on the redemption date, the
Company shall deposit with the Paying Agent money sufficient to pay the
redemption price of and accrued interest, if any, on all Securities to be
redeemed on that date.

SECTION 3.6 SECURITIES REDEEMED IN PART.

      Upon surrender of a Security that is redeemed in part, the Trustee shall
authenticate for the Holder a new Security of the same Series and the same
maturity equal in principal amount to the unredeemed portion of the Security
surrendered.

                                   ARTICLE 4.
                                    COVENANTS

SECTION 4.1 PAYMENT OF PRINCIPAL AND INTEREST.

      The Company covenants and agrees for the benefit of the Holders of each
Series of Securities that it will duly and punctually pay the principal of and
interest, if any, on the Securities of that Series in accordance with the terms
of such Securities and this Indenture.

SECTION 4.2 SEC REPORTS.

      The Company shall, so long as any of the Securities are outstanding,
deliver to the Trustee within 15 days after it files them with the SEC copies of
the annual reports and of the information, documents, and other reports (or
copies of such portions of any of the foregoing as the SEC may by rules and
regulations prescribe) which the Company is required to file with the SEC
pursuant to Section 13 or 15(d) of the Exchange Act. The Company also shall
comply with the other provisions of TIA Section 314(a). Delivery of such
reports, information and documents to the Trustee is for informational purposes
only and the Trustee's receipt of such shall not constitute constructive notice
of any information contained therein or determinable from information contained
therein, including the Company's compliance with any of its covenants hereunder
(as to which the Trustee is entitled to rely exclusively on an Officers'
Certificate).

SECTION 4.3 COMPLIANCE CERTIFICATE.

      The Company shall, so long as any of the Securities are outstanding,
deliver to the Trustee, within 120 days after the end of each fiscal year of the
Company, an Officers' Certificate stating whether or not to the knowledge of the
signers thereof the Company is in default in the performance or observance of
any of the terms, provisions and conditions hereof (without regard to any period
of grace or requirement of notice provided hereunder), and if a Default or Event
of Default shall have occurred, specifying all such Defaults or Events of
Default and the nature and status thereof of which they may have knowledge.

      The Company will, so long as any of the Securities are outstanding,
deliver to the Trustee, within thirty (30) days after becoming aware of any
Default or Event of Default, an Officers' Certificate specifying such Default or
Event of Default and what action the Company is taking or proposes to take with
respect thereto.

                                       15
<PAGE>

SECTION 4.4 STAY, EXTENSION AND USURY LAWS.

      The Company covenants (to the extent that it may lawfully do so) that it
will not at any time insist upon, plead, or in any manner whatsoever claim or
take the benefit or advantage of, any stay, extension or usury law wherever
enacted, now or at any time hereafter in force, which may affect the covenants
or the performance of this Indenture or the Securities and the Company (to the
extent it may lawfully do so) hereby expressly waives all benefit or advantage
of any such law and covenants that it will not, by resort to any such law,
hinder, delay or impede the execution of any power herein granted to the
Trustee, but will suffer and permit the execution of every such power as though
no such law has been enacted.

SECTION 4.5 CORPORATE EXISTENCE.

      Subject to Article V, the Company will do or cause to be done all things
necessary to preserve and keep in full force and effect its corporate existence
and the rights (charter and statutory), licenses and franchises of the Company;
provided, however, that the Company shall not be required to preserve any such
right, license or franchise if the Board of Directors shall determine that the
preservation thereof is no longer desirable in the conduct of the business of
the Company and its Subsidiaries taken as a whole and that the loss thereof is
not adverse in any material respect to the Holders.

SECTION 4.6 TAXES.

      The Company shall pay prior to delinquency all taxes, assessments and
governmental levies, except as contested in good faith and by appropriate
proceedings.

                                   ARTICLE 5.
                                   SUCCESSORS

SECTION 5.1 WHEN COMPANY MAY MERGE, ETC.

      The Company shall not consolidate with or merge with or into, or convey,
transfer or lease all or substantially all of its properties and assets to, any
person (a "successor person") unless:

            (a) the Company is the surviving corporation or the successor person
      (if other than the Company) is organized and validly existing under the
      laws of any U.S. domestic jurisdiction and expressly assumes the Company's
      obligations on the Securities and under this Indenture; and

            (b) immediately after giving effect to the transaction, no Default
      or Event of Default shall have occurred and be continuing.

      The Company shall deliver to the Trustee prior to the consummation of the
proposed transaction an Officers' Certificate to the foregoing effect and an
Opinion of Counsel stating that the proposed transaction and any supplemental
indenture comply with this Indenture.

SECTION 5.2 SUCCESSOR CORPORATION SUBSTITUTED.

      Upon any consolidation or merger, or any sale, lease, conveyance or other
disposition of all or substantially all of the assets of the Company in
accordance with Section 5.1, the successor corporation formed by such
consolidation or into or with which the Company is merged or to which such sale,
lease, conveyance or other disposition is made shall succeed to, and be
substituted for, and may exercise every right and power of, the Company under
this Indenture with the same effect as if such successor person has been named
as the Company herein; provided, however, that the predecessor Company in the
case of a

                                       16
<PAGE>

sale, conveyance or other disposition (other than a lease) shall be
released from all obligations and covenants under this Indenture and the
Securities.

                                   ARTICLE 6.
                              DEFAULTS AND REMEDIES

SECTION 6.1 EVENTS OF DEFAULT.

      "Event of Default," wherever used herein with respect to Securities of any
Series, means any one of the following events, unless in the establishing Board
Resolution, supplemental indenture or Officers' Certificate, it is provided that
such Series shall not have the benefit of said Event of Default:

            (a) default in the payment of any interest on any Security of that
      Series when it becomes due and payable, and continuance of such default
      for a period of 30 days (unless the entire amount of such payment is
      deposited by the Company with the Trustee or with a Paying Agent prior to
      the expiration of such period of 30 days); or

            (b) default in the payment of principal of any Security of that
      Series at its Maturity; or

            (c) default in the deposit of any sinking fund payment, when and as
      due in respect of any Security of that Series; or

            (d) default in the performance or breach of any covenant or warranty
      of the Company in this Indenture (other than a covenant or warranty for
      which the consequences of nonperformance or breach are addressed elsewhere
      in this Section 6.1 and other than a covenant or warranty that has been
      included in this Indenture solely for the benefit of Series of Securities
      other than that Series), which default continues uncured for a period of
      90 days after there has been given, by registered or certified mail, to
      the Company by the Trustee or to the Company and the Trustee by the
      Holders of not less than a majority in principal amount of the outstanding
      Securities of that Series a written notice specifying such default or
      breach and requiring it to be remedied and stating that such notice is a
      "Notice of Default" hereunder; or

            (e) the Company pursuant to or within the meaning of any Bankruptcy
      Law:

                  (i) commences a voluntary case,

                  (ii) consents to the entry of an order for relief against it
            in an involuntary case,

                  (iii) consents to the appointment of a Custodian of it or for
            all or substantially all of its property,

                  (iv) makes a general assignment for the benefit of its
            creditors, or

                  (v) generally is unable to pay its debts as the same become
            due; or

            (f) a court of competent jurisdiction enters an order or decree
      under any Bankruptcy Law that:

                  (i) is for relief against the Company in an involuntary case,

                                       17
<PAGE>

                  (ii) appoints a Custodian of the Company or for all or
            substantially all of its property, or

                  (iii) orders the liquidation of the Company, and the order or
            decree remains unstayed and in effect for 90 days; or

            (g) any other Event of Default provided with respect to Securities
      of that Series, which is specified in a Board Resolution, a supplemental
      indenture hereto or an Officers' Certificate, in accordance with Section
      2.2.18.

      The term "Bankruptcy Law" means Title 11 of the U.S. Code or any similar
federal or state law for the relief of debtors. The term "Custodian" means any
receiver, trustee, assignee, liquidator or similar official under any Bankruptcy
Law.

SECTION 6.2 ACCELERATION OF MATURITY; RESCISSION AND ANNULMENT.

      If an Event of Default with respect to Securities of any Series at the
time outstanding occurs and is continuing (other than an Event of Default
referred to in Section 6.1(e) or (f)), then in every such case the Trustee or
the Holders of not less than a majority in principal amount of the outstanding
Securities of that Series may declare the principal amount (or, if any
Securities of that Series are Discount Securities, such portion of the principal
amount as may be specified in the terms of such Securities) of and accrued and
unpaid interest, if any, on all of the Securities of that Series to be due and
payable immediately, by a notice in writing to the Company (and to the Trustee
if given by Holders), and upon any such declaration such principal amount (or
specified amount) and accrued and unpaid interest, if any, shall become
immediately due and payable. If an Event of Default specified in Section 6.1(e)
or (f) shall occur, the principal amount (or specified amount) of and accrued
and unpaid interest, if any, on all outstanding Securities shall ipso facto
become and be immediately due and payable without any declaration or other act
on the part of the Trustee or any Holder.

      At any time after such a declaration of acceleration with respect to any
Series has been made and before a judgment or decree for payment of the money
due has been obtained by the Trustee as hereinafter in this Article provided,
the Holders of a majority in principal amount of the outstanding Securities of
that Series, by written notice to the Company and the Trustee, may rescind and
annul such declaration and its consequences if all Events of Default with
respect to Securities of that Series, other than the non-payment of the
principal and interest, if any, of Securities of that Series which have become
due solely by such declaration of acceleration, have been cured or waived as
provided in Section 6.13.

      No such rescission shall affect any subsequent Default or impair any right
consequent thereon.

SECTION 6.3 COLLECTION OF INDEBTEDNESS AND SUITS FOR ENFORCEMENT BY TRUSTEE.

      The Company covenants that if:

            (a) default is made in the payment of any interest on any Security
      when such interest becomes due and payable and such default continues for
      a period of 30 days, or

            (b) default is made in the payment of principal of any Security at
      the Maturity thereof, or

            (c) default is made in the deposit of any sinking fund payment when
      and as due by the terms of a Security,

                                       18
<PAGE>

then the Company will, upon demand of the Trustee, pay to it, for the benefit of
the Holders of such Securities the whole amount then due and payable on such
Securities for principal and interest and, to the extent that payment of such
interest shall be legally enforceable, interest on any overdue principal and any
overdue interest at the rate or rates prescribed therefor in such Securities
and, in addition thereto, such further amount as shall be sufficient to cover
the costs and expenses of collection, including the reasonable compensation,
expenses, disbursements and advances of the Trustee, its agents and counsel.

      If the Company fails to pay such amounts forthwith upon such demand, the
Trustee, in its own name and as trustee of an express trust, may institute a
judicial proceeding for the collection of the sums so due and unpaid, may
prosecute such proceeding to judgment or final decree and may enforce the same
against the Company or any other obligor upon such Securities and collect the
moneys adjudged or deemed to be payable in the manner provided by law out of the
property of the Company or any other obligor upon such Securities, wherever
situated.

      If an Event of Default with respect to any Securities of any Series occurs
and is continuing, the Trustee may in its discretion proceed to protect and
enforce its rights and the rights of the Holders of Securities of such Series by
such appropriate judicial proceedings as the Trustee shall deem most effectual
to protect and enforce any such rights, whether for the specific enforcement of
any covenant or agreement in this Indenture or in aid of the exercise of any
power granted herein, or to enforce any other proper remedy.

SECTION 6.4 TRUSTEE MAY FILE PROOFS OF CLAIM.

      In case of the pendency of any receivership, insolvency, liquidation,
bankruptcy, reorganization, arrangement, adjustment, composition or other
judicial proceeding relative to the Company or any other obligor upon the
Securities or the property of the Company or of such other obligor or their
creditors, 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 on
the Company for the payment of overdue principal or interest) shall be entitled
and empowered, by intervention in such proceeding or otherwise,

            (a) to file and prove a claim for the whole amount of principal 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 the reasonable
      compensation, expenses, disbursements and advances of the Trustee, its
      agents and counsel) and of the Holders allowed in such judicial
      proceeding, and

            (b) to collect and receive any moneys or other property payable or
      deliverable on any such claims and to distribute the same, and any
      custodian, receiver, assignee, trustee, liquidator, sequestrator or other
      similar official in any such judicial proceeding is hereby authorized by
      each Holder to make such payments to the Trustee and, in the event that
      the Trustee shall consent to the making of such payments directly to the
      Holders, to pay to the Trustee any amount due it for the reasonable
      compensation, expenses, disbursements and advances of the Trustee, its
      agents and counsel, and any other amounts due the Trustee under Section
      7.7.

      Nothing herein contained shall be deemed to authorize the Trustee to
authorize or consent to or accept or adopt on behalf of any Holder 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.

                                       19
<PAGE>

SECTION 6.5 TRUSTEE MAY ENFORCE CLAIMS WITHOUT POSSESSION OF SECURITIES.

      All rights of action and claims under this Indenture or the Securities may
be prosecuted and enforced by the Trustee without the possession of any of the
Securities or the production thereof in any proceeding relating thereto, and any
such proceeding instituted by the Trustee shall be brought in its own name as
trustee of an express trust, and any recovery of judgment shall, after provision
for the payment of the reasonable compensation, expenses, disbursements and
advances of the Trustee, its agents and counsel, be for the ratable benefit of
the Holders of the Securities in respect of which such judgment has been
recovered.

SECTION 6.6 APPLICATION OF MONEY COLLECTED.

      Any money 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 money on account of principal or interest,
upon presentation of the Securities and the notation thereon of the payment if
only partially paid and upon surrender thereof if fully paid:

      First: To the payment of all amounts due the Trustee under Section 7.7;
and

      Second: To the payment of the amounts then due and unpaid for principal of
and interest on the Securities in respect of which or for the benefit of which
such money has been collected, ratably, without preference or priority of any
kind, according to the amounts due and payable on such Securities for principal
and interest, respectively; and

      Third: To the Company.

SECTION 6.7 LIMITATION ON SUITS.

      No Holder of any Security of any Series shall have any right to institute
any proceeding, judicial or otherwise, with respect to this Indenture, or for
the appointment of a receiver or trustee, or for any other remedy hereunder,
unless:

            (a) such Holder has previously given written notice to the Trustee
      of a continuing Event of Default with respect to the Securities of that
      Series;

            (b) the Holders of at least a majority in principal amount of the
      outstanding Securities of that Series shall have made written request to
      the Trustee to institute proceedings in respect of such Event of Default
      in its own name as Trustee hereunder;

            (c) such Holder or Holders have offered to the Trustee reasonable
      indemnity against the costs, expenses and liabilities to be incurred in
      compliance with such request;

            (d) the Trustee for 60 days after its receipt of such notice,
      request and offer of indemnity has failed to institute any such
      proceeding; and

            (e) no direction inconsistent with such written request has been
      given to the Trustee during such 60-day period by the Holders of a
      majority in principal amount of the outstanding Securities of that Series;

it being understood and intended that no one or more of such Holders shall have
any right in any manner whatever by virtue of, or by availing of, any provision
of this Indenture to affect, disturb or prejudice the

                                       20
<PAGE>

rights of any other of such Holders, or to obtain or to seek to obtain priority
or preference over any other of such Holders or to enforce any right under this
Indenture, except in the manner herein provided and for the equal and ratable
benefit of all such Holders.

SECTION 6.8 UNCONDITIONAL RIGHT OF HOLDERS TO RECEIVE PRINCIPAL AND INTEREST.

      Notwithstanding any other provision in this Indenture, the Holder of any
Security shall have the right, which is absolute and unconditional, to receive
payment of the principal of and interest, if any, on such Security on the Stated
Maturity or Stated Maturities expressed in such Security (or, in the case of
redemption, on the redemption date) and to institute suit for the enforcement of
any such payment, and such rights shall not be impaired without the consent of
such Holder.

SECTION 6.9 RESTORATION OF RIGHTS AND REMEDIES.

      If the Trustee or any Holder has instituted any proceeding to enforce any
right or remedy under this Indenture and such proceeding has been discontinued
or abandoned for any reason, or has been determined adversely to the Trustee or
to such Holder, then and in every such case, subject to any determination in
such proceeding, the Company, the Trustee and the Holders shall be restored
severally and respectively to their former positions hereunder and thereafter
all rights and remedies of the Trustee and the Holders shall continue as though
no such proceeding had been instituted.

SECTION 6.10 RIGHTS AND REMEDIES CUMULATIVE.

      Except as otherwise provided with respect to the replacement or payment of
mutilated, destroyed, lost or stolen Securities in Section 2.8, 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, to the extent permitted by law, prevent the
concurrent assertion or employment of any other appropriate right or remedy.

SECTION 6.11 DELAY OR OMISSION NOT WAIVER.

      No delay or omission of the Trustee or of any Holder of any Securities to
exercise any right or remedy accruing upon any Event of Default shall impair any
such right or remedy or constitute a waiver of any such Event of Default or an
acquiescence therein. Every right and remedy given by this Article or by law to
the Trustee or to the Holders may be exercised from time to time, and as often
as may be deemed expedient, by the Trustee or by the Holders, as the case may
be.

SECTION 6.12 CONTROL BY HOLDERS.

      The Holders of a majority in principal amount of the outstanding
Securities of any Series 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, with respect to the
Securities of such Series, provided that:

            (a) such direction shall not be in conflict with any rule of law or
      with this Indenture,

            (b) the Trustee may take any other action deemed proper by the
      Trustee which is not inconsistent with such direction, and

                                       21
<PAGE>

            (c) subject to the provisions of Section 6.1, the Trustee shall have
      the right to decline to follow any such direction if the Trustee in good
      faith shall, by a Responsible Officer of the Trustee, determine that the
      proceeding so directed would involve the Trustee in personal liability.

SECTION 6.13 WAIVER OF PAST DEFAULTS.

      The Holders of not less than a majority in principal amount of the
outstanding Securities of any Series may on behalf of the Holders of all the
Securities of such Series waive any past Default hereunder with respect to such
Series and its consequences, except a Default (i) in the payment of the
principal of or interest on any Security of such Series (provided, however, that
the Holders of a majority in principal amount of the outstanding Securities of
any Series may rescind an acceleration and its consequences, including any
related payment default that resulted from such acceleration) or (ii) in respect
of a covenant or provision hereof which cannot be modified or amended without
the consent of the Holder of each outstanding Security of such Series affected.
Upon any such waiver, such Default shall cease to exist, and any Event of
Default arising therefrom shall be deemed to have been cured, for every purpose
of this Indenture; but no such waiver shall extend to any subsequent or other
Default or impair any right consequent thereon.

SECTION 6.14 UNDERTAKING FOR COSTS.

      All parties to this Indenture agree, and each Holder of any Security by
his acceptance thereof shall be deemed to have agreed, that any court may in its
discretion require, in any suit for the enforcement of any right or remedy under
this Indenture, or in any suit against the Trustee for any action taken,
suffered or omitted by it as Trustee, the filing by any party litigant in such
suit of an undertaking to pay the costs of such suit, and that such court may in
its discretion assess reasonable costs, including reasonable attorneys' fees,
against any party litigant in such suit, having due regard to the merits and
good faith of the claims or defenses made by such party litigant; but the
provisions of this Section shall not apply to any suit instituted by the
Company, to any suit instituted by the Trustee, to any suit instituted by any
Holder, or group of Holders, holding in the aggregate more than 10% in principal
amount of the outstanding Securities of any Series, or to any suit instituted by
any Holder for the enforcement of the payment of the principal of or interest on
any Security on or after the Stated Maturity or Stated Maturities expressed in
such Security (or, in the case of redemption, on the redemption date).

                                   ARTICLE 7.
                                     TRUSTEE

SECTION 7.1 DUTIES OF TRUSTEE.

            (a) If an Event of Default has occurred and is continuing, the
      Trustee shall exercise 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.

            (b) Except during the continuance of an Event of Default:

                  (i) The Trustee need perform only those duties that are
            specifically set forth in this Indenture and no others.

                  (ii) In the absence of bad faith on its part, the Trustee may
            conclusively rely, as to the truth of the statements and the
            correctness of the opinions expressed therein, upon Officers'
            Certificates or Opinions of Counsel furnished to the Trustee and

                                       22
<PAGE>

            conforming to the requirements of this Indenture; however, in the
            case of any such Officers' Certificates or Opinions of Counsel which
            by any provisions hereof are specifically required to be furnished
            to the Trustee, the Trustee shall examine such Officers'
            Certificates and Opinions of Counsel to determine whether or not
            they conform to the requirements of this Indenture.

            (c) The Trustee may not be relieved from liability for its own
      negligent action, its own negligent failure to act or its own willful
      misconduct, except that:

                  (i) This paragraph does not limit the effect of paragraph (b)
            of this Section.

                  (ii) The Trustee shall not be liable for any error of judgment
            made in good faith by a Responsible Officer, unless it is proved
            that the Trustee was negligent in ascertaining the pertinent facts.

                  (iii) The Trustee shall not be liable with respect to any
            action taken, suffered or omitted to be taken by it with respect to
            Securities of any Series in good faith in accordance with the
            direction of the Holders of a majority in principal amount of the
            outstanding Securities of such Series 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 with respect to the Securities of such
            Series.

            (d) Every provision of this Indenture that in any way relates to the
      Trustee is subject to paragraph (a), (b) and (c) of this Section.

            (e) The Trustee may refuse to perform any duty or exercise any right
      or power at the request or direction of any Holder unless it receives
      indemnity satisfactory to it against any loss, liability or expense.

            (f) The Trustee shall not be liable for interest on any money
      received by it except as the Trustee may agree in writing with the
      Company. Money held in trust by the Trustee need not be segregated from
      other funds except to the extent required by law.

            (g) No provision of this Indenture shall require the Trustee to risk
      its own funds or otherwise incur any financial liability in the
      performance of any of its duties, or in the exercise of any of its rights
      or powers, if it shall have reasonable grounds for believing that
      repayment of such funds or adequate indemnity against such risk is not
      reasonably assured to it.

            (h) The Paying Agent, the Registrar and any authenticating agent
      shall be entitled to the protections, immunities and standard of care as
      are set forth in paragraphs (a), (b) and (c) of this Section with respect
      to the Trustee.

SECTION 7.2 RIGHTS OF TRUSTEE.

            (a) The Trustee may rely on and shall be protected in acting or
      refraining from acting upon any document believed by it to be genuine and
      to have been signed or presented by the proper person. The Trustee need
      not investigate any fact or matter stated in the document.

                                       23
<PAGE>

            (b) Before the Trustee acts or refrains from acting, it may require
      an Officers' Certificate. The Trustee shall not be liable for any action
      it takes or omits to take in good faith in reliance on such Officers'
      Certificate.

            (c) The Trustee may act through agents and shall not be responsible
      for the misconduct or negligence of any agent appointed with due care. No
      Depository shall be deemed an agent of the Trustee and the Trustee shall
      not be responsible for any act or omission by any Depository.

            (d) The Trustee shall not be liable for any action it takes or omits
      to take in good faith which it believes to be authorized or within its
      rights or powers, provided that the Trustee's conduct does not constitute
      negligence or bad faith.

            (e) The Trustee may consult with counsel and the advice of such
      counsel or any Opinion of Counsel shall be full and complete authorization
      and protection in respect of any action taken, suffered or omitted by it
      hereunder without negligence and in good faith and in reliance thereon.

            (f) The Trustee shall be under no obligation to exercise any of the
      rights or powers vested in it by this Indenture at the request or
      direction of any of the Holders of Securities unless such Holders shall
      have offered to the Trustee reasonable security or indemnity against the
      costs, expenses and liabilities which might be incurred by it in
      compliance with such request or direction.

            (g) The Trustee may consult with counsel of its selection and the
      advice of such counsel or any Opinion of Counsel shall be full and
      complete authorization and protection in respect of any action taken,
      suffered or omitted by it hereunder without negligence and in good faith
      and in reliance thereon.

            (h) 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.

            (i) The Trustee shall not be deemed to have notice of any Default or
      Event of Default unless a Responsible Officer of the Trustee has actual
      knowledge thereof or unless written notice of any event which is in fact
      such a default is received by the Trustee at the Corporate Trust Office of
      the Trustee, and such notice references the Securities generally or the
      Securities of a particular Series and this Indenture.

SECTION 7.3 INDIVIDUAL RIGHTS OF TRUSTEE.

      The Trustee in its individual or any other capacity may become the owner
or pledgee of Securities and may otherwise deal with the Company or an Affiliate
of the Company with the same rights it would have if it were not Trustee. Any
Agent may do the same with like rights. The Trustee is also subject to Sections
7.10 and 7.11.

                                       24
<PAGE>

SECTION 7.4 TRUSTEE'S DISCLAIMER.

      The Trustee makes no representation as to the validity or adequacy of this
Indenture or the Securities, it shall not be accountable for the Company's use
of the proceeds from the Securities, and it shall not be responsible for any
statement in the Securities other than its authentication.

SECTION 7.5 NOTICE OF DEFAULTS.

      If a Default or Event of Default occurs and is continuing with respect to
the Securities of any Series and if it is known to a Responsible Officer of the
Trustee, the Trustee shall mail to each Securityholder of the Securities of that
Series and, if any Bearer Securities are outstanding, publish on one occasion in
an Authorized Newspaper, notice of a Default or Event of Default within 90 days
after it occurs or, if later, after a Responsible Officer of the Trustee has
knowledge of such Default or Event of Default. Except in the case of a Default
or Event of Default in payment of principal of or interest on any Security of
any Series, the Trustee may withhold the notice if and so long as its corporate
trust committee or a committee of its Responsible Officers in good faith
determines that withholding the notice is in the interests of Securityholders of
that Series.

SECTION 7.6 REPORTS BY TRUSTEE TO HOLDERS.

      Within 60 days after May 15 in each year, the Trustee shall transmit by
mail to all Securityholders, as their names and addresses appear on the register
kept by the Registrar and, if any Bearer Securities are outstanding, publish in
an Authorized Newspaper, a brief report dated as of such May 15, in accordance
with, and to the extent required under, TIA Section 313.

      A copy of each report at the time of its mailing to Securityholders of any
Series shall be filed with the SEC and each stock exchange on which the
Securities of that Series are listed. The Company shall promptly notify the
Trustee when Securities of any Series are listed on any stock exchange.

SECTION 7.7 COMPENSATION AND INDEMNITY.

      The Company shall pay to the Trustee from time to time compensation for
its services as the Company and the Trustee shall from time to time agree upon
in writing. The Trustee's compensation shall not be limited by any law on
compensation of a trustee of an express trust. The Company shall reimburse the
Trustee upon request for all reasonable out-of-pocket expenses incurred by it.
Such expenses shall include the reasonable compensation and expenses of the
Trustee's agents and counsel.

      The Company shall indemnify each of the Trustee and any predecessor
Trustee (including the cost of defending itself) against any loss, liability or
expense, including taxes (other than taxes based upon, measured by or determined
by the income of the Trustee) incurred by it except as set forth in the next
paragraph in the performance of its duties under this Indenture as Trustee or
Agent. The Trustee shall notify the Company promptly of any claim for which it
may seek indemnity. The Company shall defend the claim and the Trustee shall
cooperate in the defense. The Trustee may have one separate counsel and the
Company shall pay the reasonable fees and expenses of such counsel. The Company
need not pay for any settlement made without its consent, which consent shall
not be unreasonably withheld. This indemnification shall apply to officers,
directors, employees, shareholders and agents of the Trustee.

      The Company need not reimburse any expense or indemnify against any loss
or liability incurred by the Trustee or by any officer, director, employee,
shareholder or agent of the Trustee through negligence or bad faith.

                                       25

<PAGE>

      To secure the Company's payment obligations in this Section, the Trustee
shall have a lien prior to the Securities of any Series on all money or property
held or collected by the Trustee, except that held in trust to pay principal of
and interest on particular Securities of that Series.

      When the Trustee incurs expenses or renders services after an Event of
Default specified in Section 6.1(e) or (f) occurs, the expenses and the
compensation for the services are intended to constitute expenses of
administration under any Bankruptcy Law.

      The provisions of this Section shall survive the termination of this
Indenture.

SECTION 7.8 REPLACEMENT OF TRUSTEE.

      A resignation or removal of the Trustee and appointment of a successor
Trustee shall become effective only upon the successor Trustee's acceptance of
appointment as provided in this Section.

      The Trustee may resign with respect to the Securities of one or more
Series by so notifying the Company at least 30 days prior to the date of the
proposed resignation. The Holders of a majority in principal amount of the
Securities of any Series may remove the Trustee with respect to that Series by
so notifying the Trustee and the Company. The Company may remove the Trustee
with respect to Securities of one or more Series if:

            (a) the Trustee fails to comply with Section 7.10;

            (b) the Trustee is adjudged bankrupt or insolvent or an order for
      relief is entered with respect to the Trustee under any Bankruptcy Law;

            (c) a Custodian or public officer takes charge of the Trustee or its
      property; or

            (d) the Trustee becomes incapable of acting.

      If the Trustee resigns or is removed or if a vacancy exists in the office
of Trustee for any reason, the Company shall promptly appoint a successor
Trustee. Within one year after the successor Trustee takes office, the Holders
of a majority in principal amount of the then outstanding Securities may appoint
a successor Trustee to replace the successor Trustee appointed by the Company.

      If a successor Trustee with respect to the Securities of any one or more
Series does not take office within 60 days after the retiring Trustee resigns or
is removed, the retiring Trustee, the Company or the Holders of at least a
majority in principal amount of the Securities of the applicable Series may
petition any court of competent jurisdiction for the appointment of a successor
Trustee.

      A successor Trustee shall deliver a written acceptance of its appointment
to the retiring Trustee and to the Company. Immediately after that, the retiring
Trustee shall transfer all property held by it as Trustee to the successor
Trustee subject to the lien provided for in Section 7.7, the resignation or
removal of the retiring Trustee shall become effective, and the successor
Trustee shall have all the rights, powers and duties of the Trustee with respect
to each Series of Securities for which it is acting as Trustee under this
Indenture. A successor Trustee shall mail a notice of its succession to each
Securityholder of each such Series and, if any Bearer Securities are
outstanding, publish such notice on one occasion in an Authorized Newspaper.
Notwithstanding replacement of the Trustee pursuant to this Section 7.8, the
Company's obligations under Section 7.7 hereof shall continue for the benefit of
the retiring Trustee with respect to expenses and liabilities incurred by it
prior to such replacement.

                                       26

<PAGE>

SECTION 7.9 SUCCESSOR TRUSTEE BY MERGER, ETC.

      If the Trustee consolidates with, merges or converts into, or transfers
all or substantially all of its corporate trust business to, another
corporation, the successor corporation without any further act shall be the
successor Trustee.

SECTION 7.10 ELIGIBILITY; DISQUALIFICATION.

      This Indenture shall always have a Trustee who satisfies the requirements
of TIA Section 310(a)(1), (2) and (5). The Trustee shall always have a combined
capital and surplus of at least $25,000,000 as set forth in its most recent
published annual report of condition. The Trustee shall comply with TIA Section
310(b).

SECTION 7.11 PREFERENTIAL COLLECTION OF CLAIMS AGAINST COMPANY.

      The Trustee is subject to TIA Section 311(a), excluding any creditor
relationship listed in TIA Section 311(b). A Trustee who has resigned or been
removed shall be subject to TIA Section 311(a) to the extent indicated.

                                   ARTICLE 8.
                     SATISFACTION AND DISCHARGE; DEFEASANCE

SECTION 8.1 SATISFACTION AND DISCHARGE OF INDENTURE.

      This Indenture shall upon Company Order cease to be of further effect
(except as hereinafter provided in this Section 8.1), and the Trustee, at the
expense of the Company, shall execute proper instruments acknowledging
satisfaction and discharge of this Indenture, when

            (a) either of the following shall have occurred:

                  (i) all Securities theretofore authenticated and delivered
            (other than Securities that have been destroyed, lost or stolen and
            that have been replaced or paid) have been delivered to the Trustee
            for cancellation; or

                  (ii) all such Securities not theretofore delivered to the
            Trustee for cancellation

                        (1) have become due and payable, or

                        (2) will become due and payable at their Stated Maturity
                  within one year, or

                        (3) are to be called for redemption within one year
                  under arrangements satisfactory to the Trustee for the giving
                  of notice of redemption by the Trustee in the name, and at the
                  expense, of the Company;

      and the Company has irrevocably deposited or caused to be deposited with
      the Trustee as trust funds in trust an amount sufficient for the purpose
      of paying and discharging the entire indebtedness on such Securities not
      theretofore delivered to the Trustee for cancellation, for principal and
      interest to the date of such deposit (in the case of Securities which have
      become due

                                       27

<PAGE>

      and payable on or prior to the date of such deposit) or to the Stated
      Maturity or redemption date, as the case may be;

            (b) the Company has paid or caused to be paid all other sums payable
      hereunder by the Company; and

            (c) the Company has delivered to the Trustee an Officers'
      Certificate and an Opinion of Counsel, each stating that all conditions
      precedent herein provided for relating to the satisfaction and discharge
      of this Indenture have been complied with.

Notwithstanding the satisfaction and discharge of this Indenture, the
obligations of the Company to the Trustee under Section 7.7 and, if money shall
have been deposited with the Trustee pursuant to clause (a) of this Section, the
provisions of Sections 2.4, 2.7, 2.8, 8.1, 8.2 and 8.5 shall survive.

SECTION 8.2 APPLICATION OF TRUST FUNDS; INDEMNIFICATION.

            (a) Subject to the provisions of Section 8.5, all money deposited
      with the Trustee pursuant to Section 8.1, all money and U.S. Government
      Obligations or Foreign Government Obligations deposited with the Trustee
      pursuant to Section 8.3 or 8.4 and all money received by the Trustee in
      respect of U.S. Government Obligations or Foreign Government Obligations
      deposited with the Trustee pursuant to Section 8.3 or 8.4, shall be held
      in trust and applied by it, in accordance with the provisions of the
      Securities and this Indenture, to the payment, either directly or through
      any Paying Agent (other than the Company acting as its own Paying Agent)
      as the Trustee may determine, to the persons entitled thereto, of the
      principal and interest for whose payment such money has been deposited
      with or received by the Trustee or to make mandatory sinking fund payments
      or analogous payments as contemplated by Sections 8.3 or 8.4.

            (b) The Company shall pay and shall indemnify the Trustee against
      any tax, fee or other charge imposed on or assessed against U.S.
      Government Obligations or Foreign Government Obligations deposited
      pursuant to Sections 8.3 or 8.4 or the interest and principal received in
      respect of such obligations other than any payable by or on behalf of
      Holders.

            (c) The Trustee shall deliver or pay to the Company from time to
      time upon Company Request any U.S. Government Obligations or Foreign
      Government Obligations or money held by it as provided in Sections 8.3 or
      8.4 which, in the opinion of a nationally recognized firm of independent
      certified public accountants expressed in a written certification thereof
      delivered to the Trustee, are then in excess of the amount thereof which
      then would have been required to be deposited for the purpose for which
      such U.S. Government Obligations or Foreign Government Obligations or
      money were deposited or received. This provision shall not authorize the
      sale by the Trustee of any U.S. Government Obligations or Foreign
      Government Obligations held under this Indenture.

SECTION 8.3 LEGAL DEFEASANCE OF SECURITIES OF ANY SERIES.

      Unless this Section 8.3 is otherwise specified, pursuant to Section
2.2.23, to be inapplicable to Securities of any Series, the Company shall be
deemed to have paid and discharged the entire indebtedness on all the
outstanding Securities of any Series on the 91st day after the date of the
deposit referred to in subparagraph (d) hereof, and the provisions of this
Indenture, as it relates to such outstanding Securities of such Series, shall no
longer be in effect (and the Trustee, at the expense of the Company, shall, at
Company Request, execute proper instruments acknowledging the same), except as
to:

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<PAGE>

            (a) the rights of Holders of Securities of such Series to receive,
      from the trust funds described in subparagraph (d) hereof, (i) payment of
      the principal of and each installment of principal of and interest on the
      outstanding Securities of such Series on the Stated Maturity of such
      principal or installment of principal or interest and (ii) the benefit of
      any mandatory sinking fund 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 provisions of Sections 2.4, 2.7, 2.8, 8.2, 8.3, and 8.5; and

            (c) the rights, powers, trust and immunities of the Trustee
      hereunder;

provided that, the following conditions shall have been satisfied:

            (d) the Company shall have deposited or caused to be irrevocably
      deposited (except as provided in Section 8.2(c)) with the Trustee as trust
      funds in trust for the purpose of making the following payments,
      specifically pledged as security for and dedicated solely to the benefit
      of the Holders of such Securities (i) in the case of Securities of such
      Series denominated in Dollars, cash in Dollars and/or U.S. Government
      Obligations, or (ii) in the case of Securities of such Series denominated
      in a Foreign Currency (other than a composite currency), money and/or
      Foreign Government Obligations, which through the payment of interest and
      principal in respect thereof in accordance with their terms, will provide
      (and without reinvestment and assuming no tax liability will be imposed on
      such Trustee), not later than one day before the due date of any payment
      of money, an amount in 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 and discharge each
      installment of principal of and interest, if any, on and any mandatory
      sinking fund payments in respect of all the Securities of such Series on
      the dates such installments of interest or principal and such sinking fund
      payments are due;

            (e) such deposit will not result in a breach or violation of, or
      constitute a default under, this Indenture or any other agreement or
      instrument to which the Company is a party or by which it is bound;

            (f) no Default or Event of Default with respect to the Securities of
      such Series shall have occurred and be continuing on the date of such
      deposit or during the period ending on the 91st day after such date;

            (g) the Company shall have delivered to the Trustee an Officers'
      Certificate and an Opinion of Counsel to the effect that (i) the Company
      has received from, or there has been published by, the Internal Revenue
      Service a ruling, or (ii) since the date of execution of this Indenture,
      there has been a change in the applicable Federal income tax law, in
      either case to the effect that, and based thereon such Opinion of Counsel
      shall confirm that, the Holders of the Securities of such Series will not
      recognize income, gain or loss for Federal income tax purposes as a result
      of such deposit, defeasance and discharge and will be subject to Federal
      income tax on the same amounts 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;

            (h) the Company shall have delivered to the Trustee an Officers'
      Certificate stating that the deposit was not made by the Company with the
      intent of preferring the Holders of the Securities of such Series over any
      other creditors of the Company or with the intent of defeating, hindering,
      delaying or defrauding any other creditors of the Company; and

                                       29

<PAGE>

            (i) the Company shall have delivered to the Trustee an Officers'
      Certificate and an Opinion of Counsel, each stating that all conditions
      precedent provided for relating to the defeasance contemplated by this
      Section have been complied with.

SECTION 8.4 COVENANT DEFEASANCE.

      Unless this Section 8.4 is otherwise specified pursuant to Section 2.2.23
to be inapplicable to Securities of any Series, on and after the 91st day after
the date of the deposit referred to in subparagraph (a) hereof, the Company may
omit to comply with respect to the Securities of any Series with any term,
provision or condition set forth under Sections 4.2, 4.3, 4.4, 4.6 and 5.1 as
well as any additional covenants specified in a supplemental indenture for such
Series of Securities or a Board Resolution or an Officers' Certificate delivered
pursuant to Section 2.2.23 (and the failure to comply with any such covenants
shall not constitute a Default or Event of Default with respect to such Series
under Section 6.1) and the occurrence of any event specified in a supplemental
indenture for such Series of Securities or a Board Resolution or an Officers'
Certificate delivered pursuant to Section 2.2.18 and designated as an Event of
Default shall not constitute a Default or Event of Default hereunder, with
respect to the Securities of such Series, provided that the following conditions
shall have been satisfied:

            (a) With reference to this Section 8.4, the Company has deposited or
      caused to be irrevocably deposited (except as provided in Section 8.2(c))
      with the Trustee as trust funds in trust for the purpose of making the
      following payments specifically pledged as security for, and dedicated
      solely to, the benefit of the Holders of such Securities (i) in the case
      of Securities of such Series denominated in Dollars, cash in Dollars
      and/or U.S. Government Obligations, or (ii) in the case of Securities of
      such Series denominated in a Foreign Currency (other than a composite
      currency), money and/or Foreign Government Obligations, which through the
      payment of interest and principal in respect thereof in accordance with
      their terms, will provide (and without reinvestment and assuming no tax
      liability will be imposed on such Trustee), not later than one day before
      the due date of any payment of money, an amount in cash, sufficient, in
      the opinion of a nationally recognized firm of independent certified
      public accountants expressed in a written certification thereof delivered
      to the Trustee, to pay and discharge each installment of principal of and
      interest, if any, on and any mandatory sinking fund payments in respect of
      the Securities of such Series on the dates such installments of interest
      or principal and such sinking fund payments are due;

            (b) Such deposit will not result in a breach or violation of, or
      constitute a default under, this Indenture or any other agreement or
      instrument to which the Company is a party or by which it is bound;

            (c) No Default or Event of Default with respect to the Securities of
      such Series shall have occurred and be continuing on the date of such
      deposit or during the period ending on the 91st day after such date;

            (d) The Company shall have delivered to the Trustee an Opinion of
      Counsel to the effect that Holders of the Securities of such Series will
      not recognize income, gain or loss for federal income tax purposes as a
      result of such deposit and covenant defeasance and will be subject to
      federal income tax on the same amounts, in the same manner and at the same
      times as would have been the case if such deposit and covenant defeasance
      had not occurred; and

            (e) The Company shall have delivered to the Trustee an Officers'
      Certificate and an Opinion of Counsel, each stating that all conditions
      precedent herein provided for relating to the covenant defeasance
      contemplated by this Section have been complied with.

                                       30

<PAGE>

SECTION 8.5 REPAYMENT TO COMPANY.

      The Trustee and the Paying Agent shall pay to the Company upon request any
money held by them for the payment of principal and interest that remains
unclaimed for two years. After that, Securityholders entitled to the money must
look to the Company for payment as general creditors unless an applicable
abandoned property law designates another person.

                                   ARTICLE 9.
                             AMENDMENTS AND WAIVERS

SECTION 9.1 WITHOUT CONSENT OF HOLDERS.

      The Company and the Trustee may amend or supplement this Indenture or the
Securities of one or more Series without the consent of any Securityholder:

            (a) to cure any ambiguity, defect or inconsistency;

            (b) to comply with Article V;

            (c) to provide for uncertificated Securities in addition to or in
      place of certificated Securities;

            (d) to make any change that does not adversely affect the rights of
      any Securityholder;

            (e) to provide for the issuance of and establish the form and terms
      and conditions of Securities of any Series as permitted by this Indenture;

            (f) to evidence and provide for the acceptance of appointment
      hereunder by a successor Trustee with respect to the Securities of one or
      more Series and to add to or change any of the provisions of this
      Indenture as shall be necessary to provide for or facilitate the
      administration of the trusts hereunder by more than one Trustee; or

            (g) to comply with requirements of the SEC in order to effect or
      maintain the qualification of this Indenture under the TIA.

SECTION 9.2 WITH CONSENT OF HOLDERS.

      The Company and the Trustee may enter into a supplemental indenture with
the written consent of the Holders of at least a majority in principal amount of
the outstanding Securities of each Series affected by such supplemental
indenture (including consents obtained in connection with a tender offer or
exchange offer for the Securities of such Series), for the purpose of adding any
provisions to or changing in any manner or eliminating any of the provisions of
this Indenture or of any supplemental indenture or of modifying in any manner
the rights of the Securityholders of each such Series. Except as provided in
Section 6.13, the Holders of at least a majority in principal amount of the
outstanding Securities of any Series by notice to the Trustee (including
consents obtained in connection with a tender offer or exchange offer for the
Securities of such Series) may waive compliance by the Company with any
provision of this Indenture or the Securities with respect to such Series.

      It shall not be necessary for the consent of the Holders of Securities
under this Section 9.2 to approve the particular form of any proposed
supplemental indenture or waiver, but it shall be sufficient if

                                       31

<PAGE>

such consent approves the substance thereof. After a supplemental indenture or
waiver under this section becomes effective, the Company shall mail to the
Holders of Securities affected thereby and, if any Bearer Securities affected
thereby are outstanding, publish on one occasion in an Authorized Newspaper, a
notice briefly describing the supplemental indenture or waiver. Any failure by
the Company to mail or publish such notice, or any defect therein, shall not,
however, in any way impair or affect the validity of any such supplemental
indenture or waiver.

SECTION 9.3 LIMITATIONS.

      Without the consent of each Securityholder affected, an amendment or
waiver may not:

            (a) reduce the amount of Securities whose Holders must consent to an
      amendment, supplement or waiver;

            (b) reduce the rate of or extend the time for payment of interest
      (including default interest) on any Security;

            (c) reduce the principal or change the Stated Maturity of any
      Security or reduce the amount of, or postpone the date fixed for, the
      payment of any sinking fund or analogous obligation;

            (d) reduce the principal amount of Discount Securities payable upon
      acceleration of the maturity thereof;

            (e) waive a Default or Event of Default in the payment of the
      principal of or interest, if any, on any Security (except a rescission of
      acceleration of the Securities of any Series by the Holders of at least a
      majority in principal amount of the outstanding Securities of such Series
      and a waiver of the payment default that resulted from such acceleration);

            (f) make the principal of or interest, if any, on any Security
      payable in any currency other than that stated in the Security;

            (g) make any change in Sections 6.8, 6.13, or 9.3 (this sentence);or

            (h) waive a redemption payment with respect to any Security.

SECTION 9.4 COMPLIANCE WITH TRUST INDENTURE ACT.

      Every amendment to this Indenture or the Securities of one or more Series
shall be set forth in a supplemental indenture hereto that complies with the TIA
as then in effect.

SECTION 9.5 REVOCATION AND EFFECT OF CONSENTS.

      Until an amendment is set forth in a supplemental indenture or a waiver
becomes effective, a consent to it by a Holder of a Security is a continuing
consent by the Holder and every subsequent Holder of a Security or portion of a
Security that evidences the same debt as the consenting Holder's Security, even
if notation of the consent is not made on any Security. However, any such Holder
or subsequent Holder may revoke the consent as to his Security or portion of a
Security if the Trustee receives the notice of revocation before the date of the
supplemental indenture or the date the waiver becomes effective.

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<PAGE>

      Any amendment or waiver once effective shall bind every Securityholder of
each Series affected by such amendment or waiver unless it is of the type
described in any of clauses (a) through (h) of Section 9.3. In that case, the
amendment or waiver shall bind each Holder of a Security who has consented to it
and every subsequent Holder of a Security or portion of a Security that
evidences the same debt as the consenting Holder's Security.

SECTION 9.6 NOTATION ON OR EXCHANGE OF SECURITIES.

      The Trustee may place an appropriate notation about an amendment or waiver
on any Security of any Series thereafter authenticated. The Company in exchange
for Securities of that Series may issue and the Trustee shall authenticate upon
request new Securities of that Series that reflect the amendment or waiver.

SECTION 9.7 TRUSTEE PROTECTED.

      In executing, or accepting the additional trusts created by, any
supplemental indenture permitted by this Article or the modifications thereby of
the trusts created by this Indenture, the Trustee shall be entitled to receive,
and (subject to Section 7.1) shall be fully protected in relying upon, an
Opinion of Counsel stating that the execution of such supplemental indenture is
authorized or permitted by this Indenture. The Trustee shall sign all
supplemental indentures, except that the Trustee need not sign any supplemental
indenture that adversely affects its rights.

                                   ARTICLE 10.
                                  MISCELLANEOUS

SECTION 10.1 TRUST INDENTURE ACT CONTROLS.

      If any provision of this Indenture limits, qualifies or conflicts with
another provision which is required or deemed to be included in this Indenture
by the TIA, such required or deemed provision shall control.

SECTION 10.2 NOTICES.

      Any notice or communication by the Company or the Trustee to the other, or
by a Holder to the Company or the Trustee, is duly given if in writing and
delivered in person or mailed by first-class mail:

      if to the Company:

            Lexicon Genetics Incorporated
            8800 Technology Forest Place
            The Woodlands, Texas  77381
            Attention: President and Chief Executive Officer
            Telephone: (281) 863-3000
            Facsimile: (281) 863-8095

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<PAGE>

      if to the Trustee:
            _____________________________________________
            _____________________________________________
            _____________________________________________
            Attention:___________________________________
            Telephone:___________________________________
            Facsimile:___________________________________

The Company or the Trustee by notice to the other may designate additional or
different addresses for subsequent notices or communications.

      Any notice or communication to a Securityholder shall be mailed by
first-class mail to his address shown on the register kept by the Registrar and,
if any Bearer Securities are outstanding, published in an Authorized Newspaper.
Failure to mail a notice or communication to a Securityholder of any Series or
any defect in it shall not affect its sufficiency with respect to other
Securityholders of that or any other Series.

      If a notice or communication is mailed or published in the manner provided
above, within the time prescribed, it is duly given, whether or not the
Securityholder receives it.

      If the Company mails a notice or communication to Securityholders, it
shall mail a copy to the Trustee and each Agent at the same time.

SECTION 10.3 COMMUNICATION BY HOLDERS WITH OTHER HOLDERS.

      Securityholders of any Series may communicate pursuant to TIA Section
312(b) with other Securityholders of that Series or any other Series with
respect to their rights under this Indenture or the Securities of that Series or
all Series. The Company, the Trustee, the Registrar and anyone else shall have
the protection of TIA Section 312(c).

SECTION 10.4 CERTIFICATE AND OPINION AS TO CONDITIONS PRECEDENT.

      Upon any request or application by the Company to the Trustee to take any
action under this Indenture, the Company shall furnish to the Trustee:

            (a) an Officers' Certificate stating that, in the opinion of the
      signers, all conditions precedent, if any, provided for in this Indenture
      relating to the proposed action have been complied with; and

            (b) an Opinion of Counsel stating that, in the opinion of such
      counsel, all such conditions precedent have been complied with.

SECTION 10.5 STATEMENTS REQUIRED IN CERTIFICATE OR OPINION.

      Each certificate or opinion with respect to compliance with a condition or
covenant provided for in this Indenture (other than a certificate provided
pursuant to TIA Section 314(a)(4)) shall comply with the provisions of TIA
Section 314(e) and shall include:

            (a) a statement that the person making such certificate or opinion
      has read such covenant or condition;

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<PAGE>

            (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.

SECTION 10.6 RULES BY TRUSTEE AND AGENTS.

      The Trustee may make reasonable rules for action by or a meeting of
Securityholders of one or more Series. Any Agent may make reasonable rules and
set reasonable requirements for its functions.

SECTION 10.7 LEGAL HOLIDAYS.

      Unless otherwise provided by Board Resolution, Officers' Certificate or
supplemental indenture hereto for a particular Series, a "Legal Holiday" is any
day that is not a Business Day. If a payment date is a Legal Holiday at a place
of payment, payment may be made at that place on the next succeeding day that is
not a Legal Holiday, and no interest shall accrue for the intervening period.

SECTION 10.8 NO RECOURSE AGAINST OTHERS.

      A director, officer, employee or stockholder, as such, of the Company
shall not have any liability for any obligations of the Company under the
Securities or the Indenture or for any claim based on, in respect of or by
reason of such obligations or their creation. Each Securityholder by accepting a
Security waives and releases all such liability. The waiver and release are part
of the consideration for the issue of the Securities.

SECTION 10.9 COUNTERPARTS.

      This Indenture may be executed in any number of counterparts and by the
parties hereto in separate counterparts, each of which when so executed shall be
deemed to be an original and all of which taken together shall constitute one
and the same agreement.

SECTION 10.10 GOVERNING LAWS.

      THIS INDENTURE AND THE SECURITIES SHALL BE GOVERNED BY THE LAWS OF THE
STATE OF NEW YORK APPLICABLE TO AGREEMENTS MADE AND TO BE PERFORMED IN SUCH
STATE, WITHOUT REGARD TO THE CONFLICT OF LAWS PROVISIONS THEREOF.

SECTION 10.11 NO ADVERSE INTERPRETATION OF OTHER AGREEMENTS.

      This Indenture may not be used to interpret another indenture, loan or
debt agreement of the Company or a Subsidiary of the Company. Any such
indenture, loan or debt agreement may not be used to interpret this Indenture.

SECTION 10.12 SUCCESSORS.

      All agreements of the Company in this Indenture and the Securities shall
bind its successor. All agreements of the Trustee in this Indenture shall bind
its successor.

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<PAGE>

SECTION 10.13 SEVERABILITY.

      In case any provision in this Indenture or in the Securities shall be
invalid, illegal or unenforceable, the validity, legality and enforceability of
the remaining provisions shall not in any way be affected or impaired thereby.

SECTION 10.14 TABLE OF CONTENTS, HEADINGS, ETC.

      The Table of Contents, Cross-Reference Table, and headings of the Articles
and Sections of this Indenture have been inserted for convenience of reference
only, are not to be considered a part hereof, and shall in no way modify or
restrict any of the terms or provisions hereof.

SECTION 10.15 SECURITIES IN A FOREIGN CURRENCY OR IN ECU.

      Unless otherwise specified in a Board Resolution, a supplemental indenture
hereto or an Officers' Certificate delivered pursuant to Section 2.2 of this
Indenture with respect to a particular Series of Securities, whenever for
purposes of this Indenture any action may be taken by the Holders of a specified
percentage in aggregate principal amount of Securities of all Series or all
Series affected by a particular action at the time outstanding and, at such
time, there are outstanding Securities of any Series which are denominated in a
coin or currency other than Dollars (including ECUs), then the principal amount
of Securities of such Series which shall be deemed to be outstanding for the
purpose of taking such action shall be that amount of Dollars that could be
obtained for such amount at the Market Exchange Rate at such time. For purposes
of this Section 10.15, "Market Exchange Rate" shall mean the noon Dollar buying
rate in New York City for cable transfers of that currency as published by the
Federal Reserve Bank of New York; provided, however, in the case of ECUs, Market
Exchange Rate shall mean the rate of exchange determined by the Commission of
the European Union (or any successor thereto) as published in the Official
Journal of the European Union (such publication or any successor publication,
the "Journal"). If such Market Exchange Rate is not available for any reason
with respect to such currency, the Trustee shall use, in its sole discretion and
without liability on its part, such quotation of the Federal Reserve Bank of New
York or, in the case of ECUs, the rate of exchange as published in the Journal,
as of the most recent available date, or quotations or, in the case of ECUs,
rates of exchange from one or more major banks in The City of New York or in the
country of issue of the currency in question or, in the case of ECUs, in
Luxembourg or such other quotations or, in the case of ECUs, rates of exchange
as the Trustee, upon consultation with the Company, shall deem appropriate. The
provisions of this paragraph shall apply in determining the equivalent principal
amount in respect of Securities of a Series denominated in currency other than
Dollars in connection with any action taken by Holders of Securities pursuant to
the terms of this Indenture.

      All decisions and determinations of the Trustee regarding the Market
Exchange Rate or any alternative determination provided for in the preceding
paragraph shall be in its sole discretion and shall, in the absence of manifest
error, to the extent permitted by law, be conclusive for all purposes and
irrevocably binding upon the Company and all Holders.

SECTION 10.16 JUDGMENT CURRENCY.

      The Company agrees, to the fullest extent that it may effectively do so
under applicable law, that (a) if for the purpose of obtaining judgment in any
court it is necessary to convert the sum due in respect of the principal of or
interest or other amount on the Securities of any Series (the "Required
Currency") into a currency in which a judgment will be rendered (the "Judgment
Currency"), the rate of exchange used shall be the rate at which in accordance
with normal banking procedures the Trustee could purchase in The City of New
York the Required Currency with the Judgment Currency on the day on which final

                                       36

<PAGE>
unappealable judgment is entered, unless such day is not a New York Banking Day,
then the rate of exchange used shall be the rate at which in accordance with
normal banking procedures the Trustee could purchase in The City of New York the
Required Currency with the Judgment Currency on the New York Banking Day
preceding the day on which final unappealable judgment is entered and (b) its
obligations under this Indenture to make payments in the Required Currency (i)
shall not be discharged or satisfied by any tender, any recovery pursuant to any
judgment (whether or not entered in accordance with subsection (a)), in any
currency other than the Required Currency, except to the extent that such tender
or recovery shall result in the actual receipt, by the payee, of the full amount
of the Required Currency expressed to be payable in respect of such payments,
(ii) shall be enforceable as an alternative or additional cause of action for
the purpose of recovering in the Required Currency the amount, if any, by which
such actual receipt shall fall short of the full amount of the Required Currency
so expressed to be payable, and (iii) shall not be affected by judgment being
obtained for any other sum due under this Indenture. For purposes of the
foregoing, "New York Banking Day" means any day except a Saturday, Sunday or a
legal holiday in The City of New York on which banking institutions are
authorized or required by law, regulation or executive order to close.

                                   ARTICLE 11.
                                  SINKING FUNDS

SECTION 11.1 APPLICABILITY OF ARTICLE.

      The provisions of this Article shall be applicable to any sinking fund for
the retirement of the Securities of a Series, except as otherwise permitted or
required by any form of Security of such Series issued pursuant to this
Indenture.

      The minimum amount of any sinking fund payment provided for by the terms
of the Securities of any Series is herein referred to as a "mandatory sinking
fund payment" and any other amount provided for by the terms of Securities of
such Series is herein referred to as an "optional sinking fund payment." If
provided for by the terms of Securities of any Series, the cash amount of any
sinking fund payment may be subject to reduction as provided in Section 11.2.
Each sinking fund payment shall be applied to the redemption of Securities of
any Series as provided for by the terms of the Securities of such Series.

SECTION 11.2 SATISFACTION OF SINKING FUND PAYMENTS WITH SECURITIES.

      The Company may, in satisfaction of all or any part of any sinking fund
payment with respect to the Securities of any Series to be made pursuant to the
terms of such Securities (1) deliver outstanding Securities of such Series to
which such sinking fund payment is applicable (other than any of such Securities
previously called for mandatory sinking fund redemption) and (2) apply as credit
Securities of such Series to which such sinking fund payment is applicable and
which have been repurchased by the Company or redeemed either at the election of
the Company pursuant to the terms of such Series of Securities (except pursuant
to any mandatory sinking fund) or through the application of permitted optional
sinking fund payments or other optional redemptions pursuant to the terms of
such Securities, provided that such Securities have not been previously so
credited. Such Securities shall be received by the Trustee, together with an
Officers' Certificate with respect thereto, not later than 15 days prior to the
date on which the Trustee begins the process of selecting Securities for
redemption, and shall be credited for such purpose by the Trustee at the price
specified in such Securities for redemption through operation of the sinking
fund and the amount of such sinking fund payment shall be reduced accordingly.
If as a result of the delivery or credit of Securities in lieu of cash payments
pursuant to this Section 11.2, the principal amount of Securities of such Series
to be redeemed in order to exhaust the aforesaid cash payment shall be less than
$100,000, the Trustee need not call Securities of such Series for redemption,
except upon receipt of a Company Order that such action be taken, and such cash
payment shall be held

                                       37

<PAGE>

by the Trustee or a Paying Agent and applied to the next succeeding sinking fund
payment, provided, however, that the Trustee or such Paying Agent shall from
time to time upon receipt of a Company Order pay over and deliver to the Company
any cash payment so being held by the Trustee or such Paying Agent upon delivery
by the Company to the Trustee of Securities of that Series purchased by the
Company having an unpaid principal amount equal to the cash payment required to
be released to the Company.

SECTION 11.3 REDEMPTION OF SECURITIES FOR SINKING FUND.

      Not less than 45 days (unless otherwise indicated in the Board Resolution,
supplemental indenture or Officers' Certificate in respect of a particular
Series of Securities) prior to each sinking fund payment date for any Series of
Securities, the Company will deliver to the Trustee an Officers' Certificate
specifying the amount of the next ensuing mandatory sinking fund payment for
that Series pursuant to the terms of that Series, the portion thereof, if any,
which is to be satisfied by payment of cash and the portion thereof, if any,
which is to be satisfied by delivering and crediting of Securities of that
Series pursuant to Section 11.2, and the optional amount, if any, to be added in
cash to the next ensuing mandatory sinking fund payment, and the Company shall
thereupon be obligated to pay the amount therein specified. Not less than 30
days (unless otherwise indicated in the Board Resolution, Officers' Certificate
or supplemental indenture in respect of a particular Series of Securities)
before each such sinking fund payment date the Trustee shall select the
Securities to be redeemed upon such sinking fund payment date in the manner
specified in Section 3.2 and cause notice of the redemption thereof to be given
in the name of and at the expense of the Company in the manner provided in
Section 3.3. Such notice having been duly given, the redemption of such
Securities shall be made upon the terms and in the manner stated in Sections
3.4, 3.5 and 3.6.

                  (Remainder of page intentionally left blank)

                                       38
<PAGE>

      IN WITNESS WHEREOF, the parties hereto have caused this Indenture to be
duly executed and attested, all as of the day and year first above written.

Attest:  LEXICON GENETICS INCORPORATED
         By:______________________________________
         Name:
         Its:

Attest:  [TRUSTEE]
         By:______________________________________
         Name:
         Its:

                                       39