Exchange Agreement - Dynegy Inc. and Enron Corp.


                               EXCHANGE AGREEMENT

         This EXCHANGE AGREEMENT (this "Agreement"), dated on November 9, 2001,
is by and between Dynegy Inc., an Illinois corporation ("Dynegy"), and Enron
Corp., an Oregon corporation ("Enron").

         A. Merger Agreement. Concurrently with the execution of this Agreement,
Dynegy, Stanford, Inc., a Delaware corporation, Badin, Inc., an Oregon
corporation, Sorin, Inc., an Illinois corporation, and Enron entered into an
Agreement and Plan of Merger (the "Merger Agreement").

         NOW THEREFORE, in consideration of the mutual agreements contained
herein and other good and valuable consideration, the sufficiency of which is
hereby acknowledged, the parties hereby agree as follows:

                                    ARTICLE I
                                   DEFINITIONS

         Section 1.1. Definitions. In this Agreement, unless there is something
in the subject matter or context inconsistent therewith, the following terms
shall have the respective meanings set out below (and grammatical variations of
such terms shall have corresponding meanings):

         "Authorization" shall mean any and all permits, licenses,
authorizations, orders, certificates, registrations or other approvals granted
by any Governmental Authority.

         "Certificate of Designations" means the Certificate of Designations of
the NNGC Preferred Stock.

         "Dynegy Acquisition Proposal" shall have the meaning assigned to such
term in the Merger Agreement.

         "Dynegy Exchange Event" means a termination of the Merger Agreement
pursuant to any of (i) Section 9.2(b) thereof after a public announcement of an
Enron Acquisition Proposal whether or not the Enron Acquisition Proposal is
still pending or has been consummated, (ii) Section 9.3(c) thereof or (iii)
Section 9.4(b) thereof.

         "Dynegy Exchange Option" has the meaning specified in Section 2.1
hereof.

         "Enron Acquisition Proposal" shall have the meaning assigned to such
term in the Merger Agreement.

         "Enron Common Stock" means the common stock, no par value, of Enron.

         "Enron Exchange Event" means a termination of the Merger Agreement
pursuant to any of (i) Section 9.2(c) after a public announcement of a Dynegy
Acquisition Proposal whether or not the Dynegy Acquisition Proposal is still
pending or has been consummated, (ii) Section 9.3(b) thereof or (iii) Section
9.4(c) thereof.

         "Enron Exchange Option" has the meaning specified in Section 2.2
hereof.





         "Enron Merger Ratio" has the meaning specified in Section 4.1 of the
Merger Agreement.

         "Exchange Option Ratio" has the meaning specified in Section 2.3
hereof.

         "NNGC" means Northern Natural Gas Corporation, a Delaware corporation.

         "NNGC Preferred Stock" means the Series A Preferred Stock, par value
$.01 per share, of NNGC.

         "Governmental Agency" means any federal, state, local, foreign or other
governmental agency, instrumentality, commission, authority, board or body.

         "Governmental Authority" shall mean any Governmental Agency (other than
a court) of the United States, any foreign country, or any domestic or foreign
state, and any political subdivision thereof, and shall include any
multinational authority having governmental or quasi-governmental powers.

         "HSR Act" shall mean the Hart-Scott-Rodino Antitrust Improvements Act
of 1976, as amended.

         "Law" shall mean all laws, statutes and ordinances of the United
States, any state of the United States, any foreign country, any foreign state
and any political subdivision thereof, including all decisions of courts having
the effect of law in each such jurisdiction.

         "Material Adverse Effect" shall have the meaning ascribed to such term
in the Merger Agreement.

         "Merger" shall have the meaning ascribed to such term in the Merger
Agreement.

         "Option" shall have the meaning ascribed to such term in the Option
Agreement.

         "Option Agreement" means the Option Agreement, dated as of the date
hereof, among CGNN Holding Company, Inc., a Delaware corporation, MCTJ Holding
Co. LLC, a Delaware limited liability company, Enron and Dynegy Holdings, Inc.,
a Delaware corporation.

         "Registration Rights Agreement" means the Registration Rights
Agreement, dated as of the date hereof, between Enron and Dynegy.

         "Regulation" shall mean any rule or regulation of any Governmental
Authority having the effect of Law or of any rule or regulation of any
self-regulatory organization.

         Section 1.2. Interpretations Not Affected by Headings. The division of
this Agreement into articles, sections and other portions and the insertion of
headings are for convenience of reference only and shall not affect the
construction or interpretation hereof. Unless otherwise indicated, all
references to an "Article" or "Section" followed by a number refer to the
specified Article or Section of this Agreement. The terms "this Agreement,"
"hereof," "herein" and "hereunder" and similar expressions refer to this
Agreement and not to any particular Article, Section or other portion hereof.


                                       2



         Section 1.3. Rules of Construction. Unless otherwise specifically
indicated or the context otherwise requires, (a) all references to "dollars" or
"$" mean United States dollars, (b) words importing the singular shall include
the plural and vice versa and words importing any gender shall include all
genders, and (c) "include," "includes" and "including" shall be deemed to be
followed by the words "without limitation."

                                   ARTICLE II
                                EXCHANGE OPTIONS

         Section 2.1. Dynegy Exchange Event. Upon the terms and subject to the
conditions of this Agreement, Dynegy shall have the option (the "Dynegy Exchange
Option") to exchange all, but not less than all, of its NNGC Preferred Stock for
shares of Enron Common Stock, exercisable at any time during the period of 90
days commencing on the date of the occurrence of a Dynegy Exchange Event by
giving written notice of such exercise to Enron.

         Section 2.2. Enron Exchange Event. Upon the terms and subject to the
conditions of this Agreement, Enron shall have the option (the "Enron Exchange
Option") to require Dynegy to exchange all, but not less than all, of its NNGC
Preferred Stock for shares of Enron Common Stock, exercisable at any time during
the period of 15 days commencing on the date of the occurrence of a Enron
Exchange Event by giving written notice of such exercise to Dynegy.

         Section 2.3. Exchange Option Ratio. Upon exercise of either the Dynegy
Exchange Option or the Enron Exchange Option, each share of NNGC Preferred Stock
shall be exchanged for a number of shares of Enron Common Stock determined by
multiplying (a) the quotient obtained by dividing $1,500,000 plus all accrued
and unpaid dividends thereon (whether or not declared and whether or not NNGC
has funds legally available for the payment of dividends) by $8.86 by (b) a
fraction, the numerator of which is the Enron Merger Ratio as in effect on the
date of the Merger Agreement and the denominator of which is the Enron Merger
Ratio in effect at the time of the termination of the Merger Agreement (the
"Exchange Option Ratio").

         Section 2.4. Notice; Closing Location. If Dynegy wishes to exercise the
Dynegy Exchange Option, it shall send a written notice (the date of which being
herein referred to as the "Dynegy Notice Date") to Enron specifying a date (as
it may be extended from time to time, the "Dynegy Closing Date") not earlier
than three Business Days nor later than 10 Business Days from the Dynegy Notice
Date for the closing of the exchange pursuant to the Dynegy Exchange Option (the
"Dynegy Closing"). The Dynegy Closing will take place at the offices of Vinson & Elkins, L.L.P., 1001 Fannin Street, Houston, Texas 77002.

         Section 2.5. Notice; Closing Location. If Enron wishes to exercise the
Enron Exchange Option, it shall send a written notice (the date of which being
herein referred to as the "Enron Notice Date") to Dynegy specifying a date (as
it may be extended from time to time, the "Enron Closing Date") not earlier than
three Business Days nor later than 10 Business Days from the Enron Notice Date
for the closing of the exchange pursuant to the Enron Exchange Option (the
"Enron Closing"). The Enron Closing will take place at the offices of Vinson & Elkins, L.L.P., 1001 Fannin Street, Houston, Texas 77002.

         Section 2.6. Extension. If either a Dynegy Closing or a Enron Closing
(each, a "Closing") cannot be effected by reason of the application of any Law,
Regulation or Order, the Dynegy Closing Date or Enron Closing Date, as the case
may be, shall be extended to not later 


                                       3



than the tenth Business Day following the expiration or termination of the
restriction imposed by such Law, Regulation or Order. Without limiting the
foregoing, if prior notification to, or Authorization of, any Governmental
Authority is required in connection with the exercise of the Dynegy Exchange
Option or the Enron Exchange Option, as the case may be, by virtue of the
application of such Law, Regulation or Order, Dynegy and Enron shall promptly
file the required notice or application for Authorization and Dynegy and Enron
shall expeditiously process the same.

         Section 2.7. Exchange of Certificates. At any Closing, upon the
satisfaction of the conditions set forth in Article VI, Dynegy shall deliver the
certificates representing the shares of NNGC Preferred Stock to Enron, duly
endorsed by the registered holder thereof either in blank or to Enron, and Enron
shall issue to Dynegy, the shares of Enron Common Stock issuable pursuant to
Section 2.3. The shares of Enron Common Stock to be issued shall be evidenced by
certificates registered in the name of Dynegy.

         Section 2.8. Transfer of Dynegy Exchange Option. If at any time Dynegy
has the right to exercise the Dynegy Exchange Option and the conditions
specified in Section 6.1 have not been satisfied, Dynegy will have the right to
assign its rights under this Agreement to any third party, provided that (i)
such assignee assumes all of Dynegy's obligations under this Agreement and (ii)
Dynegy shall have concurrently with such assignment transferred all of Dynegy's
NNGC Preferred Stock to such assignee.

         Section 2.9. Make-Whole Right. In the event that Dynegy is prevented
from receiving Enron Common Stock following an exercise of either the Dynegy
Exchange Option or the Enron Exchange Option, as the case may be, by reason of
the failure, after the good faith efforts of both Enron and Dynegy, to satisfy
the conditions for the issuance of Enron Common Stock to Dynegy specified in
Section 6.1 hereof, Enron shall, as promptly as practicable, take all such
action as may be necessary to:

                           (i) create a class of preferred stock of Enron (the
                  "Enron Preferred Stock") that (A) would be non-voting, (B)
                  would convert to Enron Common Stock upon a transfer of the
                  Enron Preferred Stock to any party or parties as to which the
                  conditions specified in Section 6.1 would be satisfied with
                  respect to the Enron Common Stock to be received by any such
                  party, (C) would not vote, separately as a class, with respect
                  to any merger, share exchange or other business combination,
                  (D) would participate pari passu with the Enron Common Stock
                  with respect to dividends and upon liquidation and (E) would
                  otherwise have such terms as would allow the Enron Preferred
                  Stock to have, as nearly as possible taking into account legal
                  and regulatory constraints, the same economic terms as the
                  Enron Common Stock,

                           (ii) issue such number of shares of Enron Preferred
                  Stock to Dynegy in exchange for all of its NNGC Preferred
                  Stock as would, taking into account the conversion ratio with
                  respect to such shares of Enron Preferred Stock, provide for
                  the issuance of an aggregate number of shares of Enron Common
                  Stock as would equal the aggregate number of shares of Enron
                  Common Stock that Dynegy would have been entitled to receive,
                  based on the Exchange Option Ratio, had it received Enron
                  Common Stock upon exercise of the Dynegy Exchange Option,


                                       4



                           (iii) amend the Registration Rights Agreement to
                  treat the Enron Preferred Stock as if it were Registrable
                  Common Stock (as defined in the Registration Rights
                  Agreement), and

                           (iv) if necessary to allow for the conversion of the
                  Enron Preferred Stock into Enron Common Stock in accordance
                  with the stockholder approval requirements of the NYSE, submit
                  to its stockholders for approval, with the favorable
                  recommendation of the Board of Directors, the issuance of the
                  Enron Common Stock issuable upon conversion of the Enron
                  Preferred Stock;

provided, however, that in the event that the conditions specified in Section
6.1 have not been satisfied after a period of 12 months following the date of
the exercise of the Dynegy Exchange Right, Dynegy shall have the right to elect,
by written notice to Enron, to either (i) withdraw its exercise of the Dynegy
Exchange Right and thereafter exercise its rights under the Option Agreement or
(ii) receive consideration from Enron (which may be, at the election of Enron,
in the form of cash, assets or securities, or some combination thereof) that
would have the same economic value as the Enron Common Stock that Dynegy would
have received at the time of its exercise of the Dynegy Exchange Option if the
Enron Common Stock had been issued to Dynegy as of the first anniversary date of
such exercise and Dynegy had immediately sold such Enron Common Stock on the New
York Stock Exchange or other national securities market (without discount to the
then public trading price of Enron's Common Stock). In the event an Enron
Acquisition Proposal is consummated, the surviving party shall be under the same
obligation as Enron to substitute for shares of Enron Common Stock (or Enron
Preferred Stock) the number of shares of acquiror common stock (or preferred
stock of the acquiring company) that would have been received had Dynegy been
able to receive the Enron Common Stock upon a Dynegy Exchange Option or an Enron
Exchange Option, but for the failure to satisfy the conditions of Section 6.1.

         Section 2.10. Termination of Exchange Options. The Enron Exchange
Option and the Dynegy Exchange Option shall terminate upon any of (i) the
consummation of the Merger, (ii) the exercise of the Option or (iii) the
redemption of all outstanding shares of NNGC Preferred Stock pursuant to the
Certificate of Designation.

                                  ARTICLE III
                     REPRESENTATIONS AND WARRANTIES OF ENRON

         Enron hereby represents and warrants to Dynegy as follows:

         Section 3.1. Existence. Enron is a corporation duly organized, validly
existing and in good standing under the laws of the State of Oregon and has full
corporate power and authority to conduct its business and own and operate its
properties as now conducted, owned and operated.

         Section 3.2. Authorization and Enforceability; Issuance of Enron Common
Stock.

         (a) Enron has the full power and authority and has taken all required
corporate and other action necessary to authorize and permit Enron to execute
and deliver this Agreement and to carry out the terms hereof and to issue and
deliver Enron Common Stock, and none of such actions will violate any provision
of Enron's Articles of Incorporation or Bylaws or any 


                                       5



applicable law, regulation, order, judgment or decree or rule of any stock
exchange where the Enron Common Stock is listed, or result in the breach of, or
constitute a default (or an event which, with notice or lapse of time or both
would constitute a default) under, any agreement, instrument or understanding to
which Enron is a party or by which it is bound. This Agreement constitutes a
legal, valid and binding obligation of Enron, enforceable against Enron in
accordance with its terms, except to the extent limited by (i) applicable
bankruptcy, insolvency, reorganization, moratorium and similar laws of general
application related to the enforcement of creditor's rights generally and (ii)
general principles of equity.

                  (b) The shares of Enron Common Stock that may be issued
pursuant to this Agreement have been duly authorized and, when issued and
delivered in accordance with this Agreement, will be validly issued and
outstanding and will be fully paid and nonassessable.

                  (c) The issuance and delivery of the shares of Enron Common
Stock that may be issued pursuant to this Agreement are not subject to any
preemptive right of any stockholder of Enron or to any right of first refusal or
other similar right in favor of any person which has not been waived and will
not require the approval of holders of Enron Common Stock or any other class of
Enron capital stock.

                                   ARTICLE IV
                    REPRESENTATIONS AND WARRANTIES OF DYNEGY

         Dynegy hereby represents and warrants to Enron as follows:

         Section 4.1. Existence. Dynegy is a corporation duly organized, validly
existing and in good standing under the laws of its jurisdiction of formation
and has full power and authority to conduct its business and own and operate its
properties as now conducted, owned and operated.

         Section 4.2. Authorization and Enforceability. Dynegy has the full
power and authority and has taken all action necessary to permit Dynegy to
execute and deliver this Agreement and to carry out the terms hereof and
thereof, and none of such actions will violate any provision of Dynegy's
Certificate of Incorporation or Bylaws or any applicable law, regulation, order,
judgment or decree or rule, or result in the breach of, or constitute a default
(or an event which, with notice or lapse of time or both would constitute a
default) under, any agreement, instrument or understanding to which Dynegy is a
party or by which it is bound. This Agreement constitutes a legal, valid and
binding obligation of Dynegy, enforceable against Dynegy in accordance with its
terms, except to the extent limited by (i) applicable bankruptcy, insolvency,
reorganization, moratorium and similar laws of general application related to
the enforcement of creditor's rights generally and (ii) general principles of
equity.

         Section 4.3. Investment Intent of Dynegy. Dynegy is acquiring the Enron
Common Stock for its own account for investment and not with a view to
distribution.

         Section 4.4. Status of Shares. Dynegy has been informed by Enron that
the shares of Enron Common Stock that may be issued pursuant to this Agreement
have not been registered under the Securities Act of 1933, as amended (the
"Securities Act"), or under any state securities laws and are being offered and
sold in reliance upon federal and state exemptions for transactions not
involving any public offering. Enron may place a restriction legend on the
certificates representing the shares of Enron Common Stock reflecting the
foregoing restrictions.


                                       6



         Section 4.5. Sophistication and Financial Condition; Information.
Dynegy represents and warrants to Enron that it considers itself to be an
experienced and sophisticated investor and to have such knowledge and experience
in financial and business matters as are necessary to evaluate the merits and
risks of an investment in the shares of Enron Common Stock. Dynegy is able to
bear the economic risk of this investment regarding Enron, is able to hold the
shares of Enron Common Stock indefinitely and has a sufficient net worth to
sustain a loss of its entire investment in Enron in the event such loss should
occur. Dynegy (a) has been furnished with such information about Enron and the
shares of Enron Common Stock as it has requested, (b) has made its own
independent inquiry and investigation into, and based thereon, has formed an
independent judgment concerning Enron and the shares of Enron Common Stock and
(c) is an "accredited" investor within the meaning of Regulation D of the
Securities Act, as currently in effect.

                                    ARTICLE V
                                    COVENANTS

         Section 5.1. Enron Reservation of Enron Stock. Enron shall at all times
reserve and keep available out of its authorized but unissued shares of Enron
Common Stock, solely for the purposes of issuance upon exchange of the NNGC
Preferred Stock in accordance with this Agreement, such number of shares of
Enron Common Stock as are issuable upon the exchange of all outstanding shares
of the NNGC Preferred Stock pursuant to this Agreement. All shares of Enron
Common Stock which are so issuable shall, when issued, be duly and validly
issued, fully paid and nonassessable and free from all taxes, liens and charges.
Enron shall take all such commercially reasonable actions as may be reasonably
necessary to assure that all such shares of Enron Common Stock may be so issued
without violation of any applicable law or governmental regulation or any
requirements of any domestic securities exchange upon which shares of Enron
Common Stock may be listed (except for official notice of issuance which shall
be immediately transmitted by Enron upon issuance).

         Section 5.2. Filings; Commercially Reasonable Best Efforts, Etc.

                  (a) Subject to the terms and conditions herein provided, Enron
and Dynegy shall:

                           (i) make their respective required filings under the
         HSR Act (and shall share equally all filing fees incident thereto),
         which filings shall be made promptly, and thereafter shall promptly
         make any other required submissions under the HSR Act;

                           (ii) make their respective filings, and obtain the
         consents, approvals, permits or authorizations, required to be made or
         obtained prior to the Closing with or from any governmental or
         regulatory authorities of the United States, the several states and
         non-U.S. jurisdictions (other than with respect to any applicable
         non-U.S. competition, antitrust or premerger notification laws (the
         "Non-U.S. Antitrust Laws"));

                           (iii) use their commercially reasonable best efforts
         to cooperate with one another in (A) determining which filings are
         advisable to be made with, and which consents, approvals, permits or
         authorizations are required to be obtained from, governmental or
         regulatory authorities under the Non-U.S. Antitrust Laws in connection
         with the execution and delivery of this Agreement, and the consummation
         of the 


                                       7



         transactions contemplated by this Agreement and the transactions
         contemplated hereby; and (B) timely making all such filings and timely
         seeking all such consents, approvals, permits or authorizations;

                           (iv) promptly notify each other of any communication
         concerning this Agreement or the transactions contemplated hereby to
         that party from any governmental or regulatory authority and permit the
         other party to review in advance any proposed communication concerning
         this Agreement or the transactions contemplated hereby to any
         governmental or regulatory authority;

                           (v) not agree to participate in any meeting or
         discussion with any governmental or regulatory authority in respect of
         any filings, investigation or other inquiry concerning this Agreement
         or the transactions contemplated hereby unless it consults with the
         other party in advance and, to the extent permitted by such
         governmental or regulatory authority, gives the other party the
         opportunity to attend and participate in such meeting or discussion;

                           (vi) furnish the other party with copies of all
         correspondence, filings and communications (and memoranda setting forth
         the substance thereof) between them and their subsidiaries and their
         respective representatives on the one hand, and any government or
         regulatory authority or members or any such authority's staff on the
         other hand, with respect to this Agreement and the transactions
         contemplated hereby; and

                           (vii) furnish the other party with such necessary
         information and reasonable assistance as such other party and its
         affiliates may reasonably request in connection with their preparation
         of necessary filings, registrations or submissions of information to
         any governmental or regulatory authorities, including, without
         limitation, any filings necessary or appropriate under the provisions
         of the HSR Act or any applicable Non-U.S. Antitrust Laws.

                  (b) Without limiting Section 5.2(a), Enron and Dynegy shall:

                           (i) each use commercially reasonable best efforts to
         avoid the entry of, or to have vacated, terminated or modified, any
         decree, order or judgment that would restrain, prevent or delay the
         consummation of the transactions contemplated by this Agreement; and

                           (ii) each use commercially reasonable best efforts to
         take any and all steps necessary to obtain any consents or eliminate
         any impediments to the consummation of the transactions contemplated by
         this Agreement.

                  (c) Nothing in this Agreement shall require either Dynegy or
Enron to dispose of any of its assets or to limit its freedom of action with
respect to any of its businesses, whether prior to or after the consummation of
the transactions contemplated by this Agreement, or to commit or agree to any of
the foregoing, to obtain any consents, approvals, permits or authorizations or
to remove any impediments to the consummation of the transactions contemplated
by this Agreement relating to competition, antitrust or premerger notification
laws or to avoid the entry of, or to effect the dissolution of, any injunction,
temporary restraining order or other order in any suit or proceeding relating to
competition, antitrust or premerger notification laws.


                                       8



         Section 5.3. Listing Application. Enron shall promptly prepare and
submit to the New York Stock Exchange ("NYSE") a listing application covering
the shares of Enron Common Stock issuable pursuant to the exercise of the Enron
Exchange Option and the Dynegy Exchange Option and shall use commercially
reasonable best efforts to obtain, prior to the exercise of the Enron Exchange
Option or the Dynegy Exchange Option, approval for the listing of such shares of
Enron Common Stock on the NYSE, subject to official notice of issuance.

         Section 5.4. Enron Acquisition Proposals. Enron shall not enter into
any agreement in respect of a Enron Acquisition Proposal unless in such
agreement the parties thereto expressly acknowledge and affirm the obligations
of Enron under this Agreement and the surviving party in such transaction
expressly assumes such obligations.

                                   ARTICLE VI
                                   CONDITIONS

         Section 6.1. Conditions to Enron's and Dynegy's Obligations. The
obligations of Enron and Dynegy to complete the exchange of NNGC Common Stock
for shares of Enron Common Stock upon the exercise of the Enron Exchange Option
or the Dynegy Exchange Option shall be subject to the fulfillment of the
following conditions:

                  (a) (i) Any waiting period applicable to the consummation of
the transactions contemplated by this Agreement under the HSR Act shall have
expired or been terminated, (ii) if required by law, approval of the FERC with
respect to the consummation of the transactions contemplated by this Agreement
under Section 203 of the Federal Power Act shall have been granted, (iii) the
Securities and Exchange Commission shall have taken all necessary action under
Section 9(a)(2) of the Public Utility Holding Company Act of 1935, as amended
(the "1935 Act"), and the exemptions of Enron and Dynegy from the provisions of
the 1935 Act other than Section 9(a)(2) will not change as a result of the
consummation of the transactions contemplated by this Agreement (provided that
each party will be entitled to waive satisfaction of this condition with respect
to the application of this condition to it), (iv) there shall not be pending or
threatened in writing any claim, proceeding or action by an agency of the
government of the United States, of the United Kingdom or of the European Union
seeking to restrain, prohibit or rescind any transactions contemplated by this
Agreement as an actual or threatened violation of the HSR Act, Non-U.S.
Antitrust Laws or other antitrust, competition or premerger notification, trade
regulation law, regulation or order, as applicable, or seeking to penalize a
party for completing any such transaction which in any of such cases is, in the
reasonable judgment of either Enron or Dynegy, reasonably likely to have a
Material Adverse Effect on Enron or Dynegy, (v) in the event of any review by
the U.K. Office of Fair Trading or, if applicable, the U.K. Secretary of State
for Trade and Industry, indications reasonably satisfactory to each of Enron and
Dynegy that the consummation of the transactions contemplated by this Agreement
will not be referred to the Competition Commission shall have been received or,
if the consummation of the transactions contemplated by this Agreement are
referred to the Competition Commission, indications reasonably satisfactory to
each of Enron and Dynegy that the consummation of the transactions contemplated
by this Agreement can proceed, (vi) any mandatory waiting period under any
applicable Non-U.S. Antitrust Laws (where the failure to 


                                       9



observe such waiting period referred to in this clause (vi) would, in the
reasonable judgment of either Dynegy or Enron, be reasonably likely to have a
Material Adverse Effect on Enron or Dynegy) shall have expired or been
terminated, (vii) all consents, approvals, permits and authorizations referred
to in Section 5.2(a)(ii) and (iii) shall have been obtained, and no such
consent, approval, permit or authorization shall impose or contain terms or
conditions that would, in the reasonable judgment of either Enron or Dynegy, be
reasonably likely to have a Material Adverse Effect on Enron or Dynegy, and
(viii) there shall not have been a final or preliminary administrative order
denying approval of or prohibiting the transactions contemplated by this
Agreement issued by a governmental authority with jurisdiction to enforce
applicable Non-U.S. Antitrust Laws, which order is, in the reasonable judgment
of either Enron or Dynegy, reasonably likely to have a Material Adverse Effect
on Enron or Dynegy.

                  (b) None of the parties hereto shall be subject to any decree,
order or injunction of a court of competent jurisdiction that prohibits the
consummation of the transactions contemplated hereby issued by a court of
competent jurisdiction of (i) the United States or any state or other
jurisdiction in the United States, (ii) the European Union or any member state
thereof or Canada or (iii) any other jurisdiction (the "Other Non-U.S.
Jurisdictions"); provided, however, that, prior to invoking this condition, each
party shall have complied with Section 5.2, and with respect to other matters
not covered by Section 5.2, shall have used its commercially reasonable best
efforts to have any such decree, order or injunction lifted or vacated; and no
statute, rule or regulation shall have been enacted by any governmental
authority which prohibits or makes unlawful the consummation of the transactions
contemplated by this Agreement; provided, further, that, with respect to any
decree, order, injunction, statute, rule or regulation of any Other Non-U.S.
Jurisdiction, noncompliance with such decree, order, injunction, statute, rule
or regulation would, in the reasonable judgement of either Dynegy or Enron, be
reasonably likely to have a Material Adverse Effect on Enron or Dynegy.

                  (c) The shares of Enron Common Stock to be issued pursuant to
the exercise of the Enron Exchange Option or the Dynegy Exchange Option shall
have been authorized for listing on the NYSE, subject to official notice of
issuance.

                                  ARTICLE VII
                               GENERAL PROVISIONS

         Section 7.1. Notices. Except as otherwise provided herein, any notice
required to be given hereunder shall be sufficient if in writing, and sent by
facsimile transmission or by courier service (with proof of service), or hand
delivery, addressed as follows:

                  (a) if to Enron:

                      Enron Corp.
                      1400 Smith Street
                      Houston, Texas  77002
                      Attention:  General Counsel
                      Facsimile:  (713) 853-3129


                                       10



                      with a copy to:

                      Vinson & Elkins L.L.P.
                      1001 Fannin, Suite 2300
                      Houston, Texas 77002-6760
                      Attention:  Thomas P. Mason, Esq.
                      Facsimile:  (713) 758-2346

                  (b) if to Dynegy:

                      Dynegy Inc.
                      1000 Louisiana, Suite 5800
                      Houston, Texas  77002
                      Attention: General Counsel
                      Facsimile:  (713) 507-6808

                      with a copy to:

                      Baker Botts L.L.P.
                      One Shell Plaza
                      910 Louisiana
                      Houston, Texas 77002-4995
                      Attention:  R. Joel Swanson, Esq.
                                  J. David Kirkland, Jr., Esq.
                      Facsimile:  (713) 229-1522

or to such other address as any party shall specify by written notice so given,
and such notice shall be deemed to have been delivered as of the date so
telecommunicated, personally delivered or mailed.

         Section 7.2. Assignment; Binding Effect; Benefit. Neither this
Agreement nor any of the rights, interests or obligations hereunder shall be
assigned by any of the parties hereto (whether by operation of law or otherwise)
unless the following conditions are satisfied: (a) the other party hereto
consents in writing to the assignment, and (b) in the case of an assignment by
Dynegy, (i) such assignee assumes all of Dynegy's obligations under this
Agreement and (ii) Dynegy shall have concurrently with such assignment
transferred all of its NNGC Preferred Stock to such assignee. Subject to the
preceding sentence, this Agreement shall be binding upon and shall inure to the
benefit of the parties hereto and their respective successors and assigns.
Notwithstanding anything contained in this Agreement to the contrary, nothing in
this Agreement, expressed or implied, is intended to confer on any person other
than the parties hereto or their respective heirs, successors, executors,
administrators and assigns any rights, remedies, obligations or liabilities
under or by reason of this Agreement.

         Section 7.3. Entire Agreement. This Agreement constitutes the entire
agreement among the parties with respect to the subject matter hereof and
supersedes all prior agreements and understandings among the parties with
respect thereto. No addition to or modification of any provision of this
Agreement shall be binding upon any party hereto unless made in writing and
signed by all parties hereto.


                                       11



         Section 7.4. Amendments. This Agreement may be amended by the parties
hereto, by action taken or authorized by their Boards of Directors. This
Agreement may not be amended except by an instrument in writing signed on behalf
of each of the parties hereto.

         Section 7.5. Governing Law. This Agreement shall be governed by and
construed in accordance with the laws of the State of Texas, without regard to
its rules of conflicts of laws.

         Section 7.6. Counterparts. This Agreement may be executed by the
parties hereto in separate counterparts, each of which when so executed and
delivered shall be an original, but all such counterparts shall together
constitute one and the same instrument. Each counterpart may consist of a number
of copies hereof each signed by less than all, but together signed by all of the
parties hereto.

         Section 7.7. Waivers. Except as provided in this Agreement, no action
taken pursuant to this Agreement, including, without limitation, any
investigation by or on behalf of any party, shall be deemed to constitute a
waiver by the party taking such action of compliance with any representations,
warranties, covenants or agreements contained in this Agreement. The waiver by
any party hereto of a breach of any provision hereunder shall not operate or be
construed as a waiver of any prior or subsequent breach of the same or any other
provision hereunder.

         Section 7.8. Severability. Any term or provision of this Agreement
which is invalid or unenforceable in any jurisdiction shall, as to that
jurisdiction, be ineffective to the extent of such invalidity or
unenforceability without rendering invalid or unenforceable the remaining terms
and provisions of this Agreement or affecting the validity or enforceability of
any of the terms or provisions of this Agreement in any other jurisdiction. If
any provision of this Agreement is so broad as to be unenforceable, the
provision shall be interpreted to be only so broad as is enforceable.

         Section 7.9. Enforcement of Agreement. The parties hereto agree that
irreparable damage would occur in the event that any of the provisions of this
Agreement were not performed in accordance with its specific terms or was
otherwise breached. It is accordingly agreed that the parties shall be entitled
to an injunction or injunctions to prevent breaches of this Agreement and to
enforce specifically the terms and provisions hereof, this being in addition to
any other remedy to which they are entitled at law or in equity.

         Section 7.10. No Special Damages. IN NO EVENT SHALL ANY PARTY BE LIABLE
IN RESPECT OF THIS AGREEMENT FOR EXEMPLARY, SPECIAL OR PUNITIVE DAMAGES.




                                       12




         IN WITNESS WHEREOF, the parties have executed this Agreement and caused
the same to be duly delivered on their behalf on the day and year first written
above.

                                     DYNEGY INC.



                                     By: /s/ HUGH A. TARPLEY
                                        ---------------------------------------
                                     Name:   Hugh A. Tarpley
                                     Title:  Executive Vice President

                                     ENRON CORP.



                                     By: /s/ RAYMOND M. BOWEN, JR.
                                        ---------------------------------------
                                     Name:   Raymond M. Bowen, Jr.
                                     Title:  Executive Vice President -- 
                                             Finance and Treasurer