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                                                                    EXHIBIT 4.27
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                        TRANSAMERICAN ENERGY CORPORATION,

                                   as Issuer,



                                       and



                        FIRSTAR BANK OF MINNESOTA, N.A.,

                                   as Trustee



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

                          FIRST SUPPLEMENTAL INDENTURE

                          Dated as of December 30, 1997

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



               $475,000,000 11 1/2% Senior Secured Notes due 2002

                                       and

            $1,130,000,000 13% Senior Secured Discount Notes due 2002




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         THIS FIRST SUPPLEMENTAL INDENTURE, effective as of December 30, 1997
(the "Supplemental Indenture"), is made and entered into by and among
TRANSAMERICAN ENERGY CORPORATION, a Delaware corporation (the "Company"), and
FIRSTAR BANK OF MINNESOTA, N.A. (the "Trustee"), under an Indenture dated as of
June 13, 1997, by and between the Company and the Trustee (the "Original
Indenture"). All capitalized terms used in this Supplemental Indenture that are
defined in the Original Indenture, either directly or by reference therein, have
the respective meanings assigned to them therein, except to the extent such
terms are otherwise defined in this Supplemental Indenture or the context
clearly requires otherwise.

         WHEREAS, Section 9.2 of the Original Indenture provides, among other
things, that, with the consent of the Holders of not less than a majority in
aggregate Value of then outstanding Notes or, with respect to certain matters,
not less than 66-2/3% in aggregate Value of the Notes at the time outstanding,
the Company, when authorized by Board Resolutions, and the Trustee may amend or
supplement the Original Indenture or the Security Documents or enter into an
indenture supplemental thereto for the purposes of adding any provisions to or
changing in any manner or eliminating any of the provisions of the Original
Indenture or the Security Documents or of modifying in any manner the rights of
the Holders under the Original Indenture or the Notes; and

         WHEREAS, the Company has solicited consents from the Holders of the
Notes (the "Consent Solicitation") to amendments (the "Proposed Amendments") to
(i) the Original Indenture; (ii) the Disbursement Agreement; (iii) the
TransTexas Disbursement Agreement; (iv) the Loan Agreement dated June 13, 1997,
by and between the Company and TARC; (v) the Loan Agreement dated June 13, 1997,
by and between the Company and TransTexas; and (vi) the Registration Rights
Agreement dated June 5, 1997 by and among the Company, TransTexas, TARC and
Jefferies & Company, Inc.; and

         WHEREAS, the Holders of at least 66-2/3% in aggregate Value of Notes at
the time outstanding have consented to the Proposed Amendments pursuant to the
Consent Solicitation; and

         WHEREAS, the Board of Directors of the Company has adopted resolutions
authorizing and approving the Proposed Amendments and the Company and the
Trustee are executing and delivering this Supplemental Indenture in order to
provide for such amendments;

         NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties to this Supplemental
Indenture hereby agree as follows:


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                                    ARTICLE I

                        AMENDMENTS TO ORIGINAL INDENTURE

         Section 1.01. Amended Definitions. The following definitions in 
Section 1.1 the Original Indenture are hereby amended as follows:

         (a)      Clause (ix) in the definition of "Permitted Investment" is 
         hereby amended to read in its entirety as follows:

                  (ix)    Investments and expenditures made in the ordinary 
                  course of business by TransTexas or its Subsidiaries, and of a
                  nature that is or shall have become customary in, the oil and 
                  gas business as a means of actively exploiting, exploring for,
                  acquiring, developing, processing, gathering, marketing or
                  transporting oil or gas or providing services with respect to
                  such activities through agreements, transactions, interests or
                  arrangements which permit a person to share risks or costs,
                  comply with regulatory requirements regarding local ownership
                  or satisfy other objectives customarily achieved through the
                  conduct of the oil and gas business jointly with third
                  parties, including, without limitation, (a) ownership
                  interests in oil and gas properties or gathering systems and
                  (b) Investments and expenditures in the form of or pursuant to
                  operating agreements, processing agreements, farm-in
                  agreements, farm-out agreements, development agreements, area
                  of mutual interest agreements, unitization agreements, pooling
                  arrangements, joint bidding agreements, service contracts,
                  joint venture agreements, partnership agreements (whether
                  general or limited), subscription agreements, stock purchase
                  agreements and other similar agreements with third parties
                  (including Unrestricted Subsidiaries); provided, that in the
                  case of any joint venture primarily engaged in processing,
                  gathering, marketing or transporting oil or gas (i) all Debt
                  of such joint venture (other than a joint venture that is an
                  Unrestricted Subsidiary) that would not otherwise constitute
                  Debt of one of the TransTexas Entities shall be deemed Debt of
                  TransTexas in proportion to its direct or indirect ownership
                  interest in such joint venture and (ii) such joint venture
                  shall be reasonably calculated to enhance the value of the
                  reserves of the TransTexas Entities or marketability of
                  production from such reserves;

         (b)      Clause (d) in the definition of "Permitted TARC Liens" is 
         hereby amended to read in its entirety as follows:

                  (d)    easements, servitudes, rights-of-way, zoning, similar
                  restrictions and other similar encumbrances or title defects
                  incurred in the ordinary course of business which, in the
                  aggregate, are not material in amount and which do not, in any
                  case, materially detract from the value of the property
                  subject thereto (as such property is used by any of the TARC
                  Entities) or materially interfere with the ordinary conduct of
                  the business of any of the 

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                  TARC Entities including, without limitation, any easement or
                  servitude granted in connection with the Port Commission Bond
                  Financing;

         (c)      Clause (s) in the definition of "Permitted TARC Liens" is 
         hereby amended to read in its entirety as follows:

                  (s)    Liens on the proceeds of any property that is not
                  Collateral, on the proceeds of any Debt Incurred in accordance
                  with the provisions hereof, or on deposit accounts containing
                  any such proceeds;

         (d)      The definition of "Permitted TARC Liens" is hereby amended by
         deleting the word "and" immediately preceding "(y)" and inserting in
         lieu thereof a ";", and by adding the following after clause (y):

                  ; and (z) Liens on any property of TARC and any agreement to
                  grant such Liens; provided that such Liens may not be granted,
                  and any agreement to grant such Liens shall not obligate TARC
                  to grant such liens, until the TARC Intercompany Loan has been
                  paid in full and has not been refinanced, refunded or replaced
                  with the proceeds of other Debt ("Other Debt"), which Other
                  Debt has a lower cost of capital to TARC than the TARC
                  Intercompany Loan and the principal amount of such Other Debt
                  (or, if such Other Debt is issued with original issued
                  discount, the original issue price of such Other Debt) is
                  equal to or less than the original price of, plus amortization
                  of the original issue discount on, the TARC Intercompany Loan
                  at the time of the Incurrence of such Other Debt.

         (e)      Clause (s) in the definition of "Permitted TransTexas Liens" 
         is hereby amended to read in its entirety as follows:

                  (s)    Liens on the proceeds of any property that is not
                  Collateral, on the proceeds of any Debt Incurred in accordance
                  with the provisions hereof, or on deposit accounts containing
                  any such proceeds;

         (f)      The definition of "Port Commission Bond Financing" is hereby
         amended to read in its entirety as follows:

                           "Port Commission Bond Financing" means a financing
                  transaction involving the following elements: (a) the transfer
                  (including, without limitation, transfer by sale, lease, lien
                  or mortgage) of TARC's interest in all or some of the
                  following assets (together with the granting, at TARC's
                  discretion, of any easements or servitudes reasonably
                  necessary to the ownership and operation of such assets by the
                  transferee) which are under construction in or near TARC's
                  refinery: (i) the Prospect Road tank farm and other tanks;
                  (ii) certain dock improvements; (iii) the dock vapor recovery
                  system; (iv) the coke handling system; (v) the refinery waste
                  water treatment facility and (vi) tankage for liquefied
                  petroleum gas (the "Port Facility Assets") to the Port of
                  South Louisiana Commission (the "Tax-Exempt Issuer") or its
                  affiliate and a leaseback of the Port Facility Assets to TARC
                  or one of its Subsidiaries; (b) the issuance of tax-exempt
                  bonds by the Tax-Exempt Issuer; and (c) the 

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                  loan of proceeds from such bonds to TARC or one of its 
                  Subsidiaries for the purpose of financing the completion of 
                  the Port Facility Assets.

        Section 1.02. Section 4.7 of the Original Indenture. Section 4.7(a) of
the Original Indenture is hereby amended to read in its entirety as follows:

                  (a) The Company shall deliver to the Trustee within 60 days
        after the end of each of its fiscal quarters, or 105 days after the end
        of a fiscal quarter that is also the end of a fiscal year, an Officers'
        Certificate complying with Section 314(a)(4) of the TIA and stating
        that a review of its activities and the activities of its Subsidiaries
        during the preceding fiscal quarter has been made under the supervision
        of the signing Officers with a view to determining whether the Company
        and its Subsidiaries have kept, observed, performed and fulfilled its
        obligations (excluding those obligations addressed by Section 12.3)
        under this Indenture and further stating, as to each such Officer
        signing such certificate, regardless of whether the signer knows of any
        failure by the Company or any Subsidiary of the Company to comply with
        any conditions or covenants in this Indenture, or of the occurrence of
        any Default, and, if such signer does know of such a failure to comply
        or Default, the certificate shall describe such failure or Default with
        particularity.

        Section 1.03. Section 4.11 of the Original Indenture. Section 4.11 of 
the Original Indenture is hereby amended as follows:

        (a)    Section 4.11(1)(r) of the Original Indenture is hereby amended to
        read in its entirety as follows:

                  (r)    Debt of TransTexas owed to the Company which together 
        with any Debt Incurred pursuant to clauses (2)(p), (3)(v) and (4)(t) 
        hereof does not in the aggregate exceed $50,000,000 principal amount
        outstanding at any one time; provided that such Debt must have a
        maturity date which is not after the maturity date of the Notes; and
        provided further, that such loan must bear cash interest which,
        together with (A) working capital available to the Company and (B) any
        cash interest payable on (i) Debt Incurred pursuant to clauses (2)(p),
        (3)(v) and (4)(t) hereof, (ii) the TARC Intercompany Loan, (iii) the
        TransTexas Intercompany Loan and (iv) any other intercompany loan
        payable to the Company, is sufficient to satisfy all interest payments
        on the Notes through their stated maturity.

        (b)    Section 4.11(2)(g) of the Original Indenture is hereby amended
        to read in its entirety as follows:

                  (g)    Any guaranty of Debt permitted by clauses (c), (d), (f)
        or (r) hereof which guaranty is subordinated in right of payment to the
        Notes and the TARC Intercompany Loan to the same extent that the Debt
        permitted to be Incurred pursuant to such clauses would be required to
        be subordinated to the Notes and the TARC Intercompany Loan and which
        guaranty shall not be included in the determination of the amount of
        Debt which may be Incurred pursuant to (c), (d), (f) or (r) hereof;

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        (c)       Section 4.11(2)(l) of the Original Indenture is hereby amended
        to read in its entirety as follows:

                  (l)    Debt or Attributable Debt Incurred in connection with 
        the acquisition of tank storage and related facilities in the vicinity
        of the refinery or a Sale and Leaseback Transaction with respect 
        thereto;

        (d)       Section 4.11(2)(p) of the Original Indenture is hereby amended
        to read in its entirety as follows:

                  (p)    Debt of TARC owed to the Company which together with 
        any Debt Incurred pursuant to clauses (1)(r), (3)(v) and (4)(t) hereof 
        does not in the aggregate exceed $50,000,000 principal amount
        outstanding at any one time; provided that such Debt must have a
        maturity date which is not after the maturity date of the Notes; and
        provided further, that such loan must bear cash interest which,
        together with (A) working capital available at the Company and (B) any
        cash interest payable on (i) Debt Incurred pursuant to clauses (1)(r),
        (3)(v) and (4)(t) hereof, (ii) the TARC Intercompany Loan, (iii) the
        TransTexas Intercompany Loan and (iv) any other intercompany loan
        payable to the Company, is sufficient to satisfy all interest payments
        on the Notes through their stated maturity;

        (e)       Section 4.11(2)(q) of the Original Indenture is hereby amended
        to read in its entirety as follows:

                  (q)    TARC may Incur Debt as an extension, renewal, 
        replacement, or refunding of any of the Debt permitted to be Incurred 
        by clauses (e), (1) or (r) hereof, or this clause (q) (such Debt is 
        collectively referred to as "Pre-Phase I TARC Refinancing Debt"), 
        provided, that (1) the maximum principal amount of Pre-Phase I TARC 
        Refinancing Debt (or, if such Pre- Phase I TARC Refinancing Debt is 
        issued with original issue discount, the original issue price of such 
        Pre-Phase I TARC Refinancing Debt) permitted under this clause (q) 
        may not exceed the lesser of (x) the principal amount of the Debt being
        extended, renewed, replaced, or refunded plus Refinancing Fees or (y) 
        if such Debt being extended, renewed, replaced, or refunded was issued
        at an original issue discount, the original issue price, plus 
        amortization of the original issue discount as of the time of the 
        Incurrence of the Pre-Phase I TARC Refinancing Debt plus Refinancing 
        Fees, (2) the Pre-Phase I TARC Refinancing Debt has a Weighted Average
        Life and a final maturity that is equal to or greater than the Debt 
        being extended, renewed, replaced, or refunded at the time of such 
        extension, renewal, replacement, or refunding and (3) the Pre-Phase I 
        TARC Refinancing Debt shall rank with respect to the Notes and the TARC
        Intercompany Loan to an extent no less favorable in respect thereof to
        the Holders than the Debt being refinanced; and

        (f)       Section 4.11(2) of the Original Indenture is hereby amended by
        adding the following after clause (q):

                  (r)    Subordinated Debt of TARC with initial proceeds to TARC
        not in excess of $200,000,000.

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        (g)       Section 4.11(3)(v) of the Original Indenture is hereby amended
        to read in its entirety as follows:

                  (v)    Debt of TransTexas owed to the Company which together 
        with any Debt Incurred pursuant to clauses (1)(r), (2)(p) and (4)(t) 
        hereof does not in the aggregate exceed $50,000,000 principal amount
        outstanding at any one time; provided that such Debt must have a
        maturity date which is not after the maturity date of the Notes; and
        provided further, that such loan must bear cash interest which,
        together with (A) working capital available to the Company and (B) any
        cash interest payable on (i) Debt Incurred pursuant to clauses (1)(r),
        (2)(p) and (4)(t) hereof, (ii) the TARC Intercompany Loan, (iii) the
        TransTexas Intercompany Loan and (iv) any other intercompany loan
        payable to the Company, is sufficient to satisfy all interest payments
        on the Notes through their stated maturity.

        (h)       Section 4.11(4)(c) of the Original Indenture is hereby amended
        to read in its entirety as follows:

                  (c)    Subordinated Debt of TARC with initial proceeds to TARC
        not in excess of $200,000,000 in the aggregate, less the aggregate
        proceeds received by TARC from the issuance of Subordinated Debt
        pursuant to Section 4.11(2)(r) above;

        (i)       Section 4.11(4)(j) of the Original Indenture is hereby amended
        to read in its entirety as follows:

                  (j)    TARC may Incur Debt as an extension, renewal, 
        replacement, or refunding of any of the Debt permitted to be Incurred 
        by clauses (c) or (g) above, the fourth paragraph of this section, this
        clause (j), clause (r) below or Debt permitted to be refinanced 
        pursuant to clause (2)(q) hereof (such Debt is collectively referred to
        as "TARC Refinancing Debt"), that (1) the maximum principal amount of 
        TARC Refinancing Debt (or, if such TARC Refinancing Debt is issued with
        original issue discount, the original issue price of such TARC
        Refinancing Debt) permitted under this clause (j) may not exceed the
        lesser of (x) the principal amount of the Debt being extended, renewed,
        replaced, or refunded plus Refinancing Fees, or (y) if such Debt being
        extended, renewed, replaced, or refunded was issued at an original
        issue discount, the original issue price, plus amortization of the
        original issue discount at the time of the Incurrence of the TARC
        Refinancing Debt plus Refinancing Fees, (2) the TARC Refinancing Debt
        has a Weighted Average Life and a final maturity that is equal to or
        greater than the Debt being extended, renewed, replaced. or refunded at
        the time of such extension, renewal, replacement, or refunding and (3)
        the TARC Refinancing Debt shall rank with respect to the Notes and the
        TARC Intercompany Loan to an extent no less favorable in respect
        thereof to the Holders than the Debt being refinanced;

        (j)       Section 4.11(4)(t) of the Original Indenture is hereby amended
        to read in its entirety as follows:

                  (t)    Debt of TARC owed to the Company which together with 
        any Debt Incurred pursuant to clauses (1)(r), (2)(p) and (3)(v) hereof
        does not in the aggregate exceed $50,000,000 principal amount 
        outstanding at any one time; provided that such Debt must have a 
        maturity date which is not after the maturity date of the Notes; and 
        provided further, 
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        that such loan must bear cash interest which, together with (A) working
        capital available to the Company and (B) any cash interest payable on 
        (i) Debt Incurred pursuant to clauses (1)(r), (2)(p) and (3)(v) hereof,
        (ii) the TARC Intercompany Loan, (iii) the TransTexas Intercompany Loan
        and (iv) any other intercompany loan payable to the Company, is 
        sufficient to satisfy all interest payments on the Notes through their
        stated maturity.

        (k)       Section 4.11(5)(d) of the Original Indenture is hereby amended
        to read in its entirety as follows:

                  (d)    Subordinated Debt of the Company with initial net 
         proceeds to the Company not in excess of $50,000,000 in the aggregate.

                                   ARTICLE II

                               GENERAL PROVISIONS

        Section 2.01. Effectiveness of Amendments. This Supplemental Indenture
is effective as of the date first above written.

        Section 2.02. Ratification of Indenture. The Original Indenture is in
all respects acknowledged, ratified and confirmed, and shall continue in full
force and effect in accordance with the terms thereof and as supplemented by
this Supplemental Indenture. The Original Indenture and this Supplemental
Indenture, shall be read, taken and construed as one and the same instrument.

        Section 2.03. Certificate and Opinion as to Conditions Precedent. 
Simultaneously with and as a to the execution of this Supplemental Indenture, 
the Company is delivering to the Trustee:

                  (a)    an Officers' Certificate in the form attached hereto 
                  as Exhibit A; and

                  (b)    an Opinion of Counsel covering the matters described in
                  Exhibit B attached hereto.

        Section 2.04. Effect of Headings. The Article and Section headings in
this Supplemental Indenture are for convenience only and shall not affect the
construction of this Supplemental Indenture.

        Section 2.05. Governing Law. THIS SUPPLEMENTAL INDENTURE SHALL BE
CONSTRUED IN ACCORDANCE WITH AND GOVERNED BY THE LAWS OF THE STATE OF NEW YORK,
AS APPLIED TO CONTRACTS MADE AND PERFORMED WITHIN THE STATE OF NEW YORK, WITHOUT
REGARD TO PRINCIPLES OF CONFLICTS OF LAW.

        Section 2.06. Counterparts. This Supplemental Indenture may be executed
in any number if counterparts, each of which so executed shall be deemed to be
an original, but all such counterparts shall together constitute the same
instrument.


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        IN WITNESS WHEREOF, the parties to this Supplemental Indenture have
caused the Supplemental Indenture to be duly executed, and their respective
corporate seals to be hereunto affixed and attached, on and effective as of day
and year first above written.




                                       TRANSAMERICAN ENERGY CORPORATION



Attest:                                By:
       ---------------------              ---------------------------------
         Tim Moore,                    Ed Donahue,
         Assistant Secretary           Vice President, Chief Financial Officer
                                       and Secretary


                                       FIRSTAR BANK OF MINNESOTA, N.A.,
                                       Trustee



                                       By:
                                          ---------------------------------
                                       Frank P. Leslie, III,
                                       Vice President



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