Document:

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                                                                   EXHIBIT 10.28
                                                                   -------------

                           OPTION PURCHASE AGREEMENT
                           -------------------------

     THIS AGREEMENT is made this 28th day of February, 2000, between GOTHIC
ENERGY CORPORATION, an Oklahoma corporation ("GEC"), GOTHIC PRODUCTION COMPANY,
an Oklahoma corporation ("GPC" and, jointly and severally with GEC, the
"Buyer"), and CHESAPEAKE EXPLORATION LIMITED PARTNERSHIP, an Oklahoma limited
partnership, successor in interest by merger to Chesapeake Gothic Corp. (the
"Seller").

                               R E C I T A L S :

     WHEREAS, the Seller owns (a) 61,007.474 shares of GEC's Senior Redeemable
Preferred Stock, Series B, $0.05 par value per share, (b) the right to receive
accrued and unpaid dividends on such Preferred Stock payable in kind, and (c)
2,394,125 shares of GEC's Common Stock, $0.01 par value per share (collectively,
the "GEC Securities");

     WHEREAS, the Seller and one or more of the wholly owned subsidiaries of
Chesapeake Energy Corporation (collectively, the "CEC Parties"), and the Buyer
and the Buyer's affiliated entities (collectively, the "Gothic Parties") are
parties to that certain Sale and Participation Agreement dated as of March 31,
1998, as amended (the "Participation Agreement") pursuant to which:  (a) the
Seller acquired an undivided fifty percent (50%) interest in certain oil, gas
and related assets from the Gothic Parties, (b) the CEC Parties and the Gothic
Parties provided for the maintenance, joint development and operation of the
Existing Acreage, the Related Interests and the Acquisition Acreage (as those
terms are defined in the Participation Agreement), and (c) an area of mutual
interest was created among the CEC Parties and the Gothic Parties covering lands
located in the States of Arkansas, Kansas, New Mexico (excluding the Pecos Slope
Acreage), Oklahoma and Texas;

     WHEREAS, the Buyer desires to purchase an option to acquire all of the
Seller's GEC Securities (the "Option") pursuant to the Option Agreement in the
form at Schedule "A" attached as a part hereof (the "Option Agreement") which
the Seller is willing to sell to the Buyer in exchange for certain modifications
to the Participation Agreement and the performance of certain other agreements
and documents set forth herein, all subject to the terms and conditions set
forth in this Agreement;

     WHEREAS, one or more of the Discount Noteholders (as hereinafter defined)
have made the execution and delivery of this Agreement and the Option a
condition precedent to the Discount Noteholders entering into agreements to
convert the debt held by such parties to equity of the Buyer.

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

1.   Purchase and Sale.  Subject to the terms and conditions set forth in this
     -----------------
Agreement, the Seller hereby agrees to sell the Option and the Buyer hereby
agrees to purchase the Option and perform the Purchase Consideration.

2.   Purchase Consideration.  Upon satisfaction or waiver of the conditions
     ----------------------
precedent set forth in paragraph 3 hereof in accordance with the terms thereof,
and in consideration for the sale of the Option to the Buyer and as a condition
precedent to the effectiveness of such grant, the Buyer will cause the Gothic
Parties to take the following actions (the"Purchase Consideration") on the
Closing Date (as hereinafter defined):

     2.1  Operations.   The Gothic Parties will take all actions necessary to
          ----------
          turn over to the CEC Parties operations on: (a) the wells identified
          at Schedule "2.1" attached as a part hereof; and (b) all wells which
          have been or are currently being developed under the Participation
          Agreement and all other wells now or hereafter proposed which are
          located in:  (i) Meade and Clark Counties, Kansas, and (ii) Texas,
          Beaver, Harper, Ellis, Woods, Woodward, Dewey, Major, Blaine (Township
          19N only), Custer, Grady, Pittsburg, Haskell, Latimer (except for
          Sections 19-36 of Township 3N Range 20E) and LeFlore Counties,
          Oklahoma, by permanently resigning as operator and waiving any rights
          under the Participation Agreement to become operator of such wells in
          the future. On
<PAGE>

          the Closing Date the Gothic Parties will execute and deliver
          resignation of operator letters in form and substance satisfactory to
          the Seller and will vote all of the Gothic Parties' interests in such
          properties for the Chesapeake Parties as successor operator (the
          "Operator Documents").

     2.2  Extensions and Right of First Refusal.  The Gothic Parties take all
          -------------------------------------
          actions necessary to: (a) extend the term of the reassignment
          obligation under paragraph 1.3 of the Participation Agreement until
          April 30, 2006; (b) extend the Termination Date (as defined in
          paragraph 14 of the Participation Agreement) until April 30, 2006, for
          the portion of the Participation Area included in the States of
          Arkansas, Kansas and Oklahoma and the portion of the State of Texas
          located north of latitude 34 degrees N; (c) amend the default and
          remedies provisions under paragraph 13 of the Participation Agreement;
          and (d) grant the CEC Parties preferential purchase and related rights
          with respect to sales of assets covered by the Participation
          Agreement. In order to evidence such extension, the parties will
          execute and deliver the Amendment Documents (as defined below)
          simultaneously with the execution of this Agreement.

3.   Conditions Precedent to Option Grant.  Unless waived in writing by the
     ------------------------------------
Buyer and the Seller, the sale of the Option pursuant to this Agreement is
subject to the satisfaction of all of the following conditions precedent on or
before March 14, 2000 (the "Condition Satisfaction Period"), unless extended in
writing by the Seller:

     3.1  Authorization.  The terms of this Agreement and the Option will have
          -------------
          been duly authorized by the respective Boards of Directors of the
          Buyer and the Seller.

     3.2  Consents.  The Buyer and the Seller will have received required
          --------
          written consents to the terms and conditions of this Agreement from
          the holders of the Buyer's 14 1/8% Senior Secured Discount Notes (the
          "Discount Noteholders"), Bank One, Texas, N.A., and any other
          necessary parties.

     3.3  No Actions.  No actions will have been taken or threatened to prevent
          ----------
          any party from entering into of this Agreement, performing this
          Agreement or seeking other relief as a result of this Agreement.

     3.4  Discount Noteholders.  The Discount Noteholders and the Gothic Parties
          --------------------
          will have executed and delivered the instruments necessary to evidence
          the agreement of the Discount Noteholders to convert all of the notes
          held by the Discount Noteholders into equity of the Buyer.

     3.5  Additional Documents.  The Gothic Parties and the CEC Parties will
          --------------------
          have each executed and delivered to the other parties such additional
          documents and instruments as might be reasonably requested by the
          Buyer or the Seller to consummate this Agreement.

     3.6  JIB Payments.  The Gothic Parties and the CEC Parties will have each
          ------------
          paid current all joint interest billings owing to the parties as
          required by the Joint Operating Agreements attached to the
          Participation Agreement.

4.   Closing.  Unless extended in writing by the Seller, the transactions
     -------
contemplated by this Agreement will be consummated on the date (the "Closing
Date") which is two (2) business days after the date all of the conditions under
paragraph 3 of  this Agreement have been satisfied in full or waived in writing
by the Buyer and the Seller.

     4.1  Seller's Deliveries.  Subject to the terms and conditions of this
          -------------------
          Agreement and the performance of the Buyer's obligations under
          paragraph 4.2 of this Agreement, on the Closing Date the Seller will
          deliver or cause to be delivered to the Buyer the following items (all
          documents will be duly executed and acknowledged where required):

          4.1.1  Option.  The Option and the Amendment Documents (as hereinafter
                 ------
                 defined);

                                      -2-
<PAGE>

          4.1.2  Evidence of Authority.  Such resolutions, certificates of good
                 ---------------------
                 standing, incumbency certificates and other evidence of
                 authority with respect to the Seller as might be reasonably
                 requested by the Buyer;

          4.1.3  Additional Documents.  Such additional documents as might be
                 --------------------
                 reasonably requested by Gothic to consummate this Agreement.

     4.2  Buyer's Deliveries.  On the Closing Date, the Buyer will deliver or
          ------------------
          cause to be delivered to the Seller the following items (all documents
          will be duly executed and acknowledged where required):

          4.2.1  Purchase Consideration.  The Gothic Parties will have each
                 ----------------------
                 executed and delivered to the Seller the Second Amendment to
                 Participation Agreement in the form of Schedule "4.2.1"
                 attached hereto as a part hereof and the other documents
                 contemplated thereby (the "Amendment Documents"), the Operator
                 Documents and any other documents required to evidence the
                 Purchase Consideration;

          4.2.2  Evidence of Authority.  Such corporate resolutions,
                 ---------------------
                 certificates of good standing, incumbency certificates and
                 other evidence of authority with respect to each of the Gothic
                 Parties as might be reasonably requested by the Seller;

          4.2.3  Additional Documents.  Such additional documents as might be
                 --------------------
                 reasonably requested by the Seller to consummate this
                 Agreement.

5.   Seller Representations and Warranties.  The Seller hereby represents and
     -------------------------------------
warrants to the Buyer that:

     5.1  Title.   The Seller has good and valid title to the GEC Securities,
          -----
          free and clear of all liens, claims and encumbrances.

     5.2  Authority and Reliance.  The Seller has taken all necessary action to
          ----------------------
          authorize the execution, delivery and performance of this Agreement,
          the Amendment Documents, the Operator Documents and the Option
          Agreement and has adequate power, authority and legal right to enter
          into, execute, deliver and perform this Agreement and to issue the
          Option as contemplated hereby.

     5.3  Consents.    No consent, approval, license, qualification or formal
          --------
          exemption from, nor any filing, declaration or registration with, any
          court, governmental agency or regulatory authority or any securities
          exchange is required in connection with the execution, delivery or
          performance by the Seller of this Agreement.

     5.4  Litigation. There is no action, suit, investigation or proceeding,
          ----------
          governmental or otherwise, pending or, to the best knowledge of the
          Seller, threatened to which any of the CEC Parties is or would be a
          party which seeks to restrain, enjoin, prevent the consummation of or
          otherwise challenge this Agreement or the Seller's granting of the
          Option or questions the legality or validity of any such transactions
          or seeks to recover damages or obtain other relief in connection with
          any such transactions.

6.   Buyer Representations and Warranties.  The Buyer hereby represents and
     ------------------------------------
warrants to the Seller that:

     6.1  Authority and Reliance.  The Buyer has taken all necessary action to
          ----------------------
          authorize the execution, delivery and performance of this Agreement,
          the Amendment Documents, the Operator Documents and the Option
          Agreement and has all requisite corporate power, authority and legal
          right to enter into, execute, deliver and perform this Agreement, the
          Amendment Documents, the Operator Documents and the Option Agreement.
          The Buyer further represents and warrants that,

                                      -3-
<PAGE>

          in purchasing the Option, the Buyer has relied upon independent
          investigations made by the Buyer or the Buyer's representatives, that
          the Buyer has had sufficient opportunities to make inquiries of the
          Seller and that the Buyer and such representatives have been given the
          opportunity to examine all documents concerning the terms and
          conditions of the Option. The Buyer represents and warrants that the
          Buyer is experienced in the oil and gas business, has knowledge and
          experience in business and financial matters and is competent to
          evaluate the value of the Option and the benefits and risks relating
          to the purchase of the Option and the Buyer has determined that the
          consideration being given by the Buyer is the fair value equivalent of
          the consideration being received by the Buyer for the granting of the
          Option.

     6.2  Consents.  The Buyer has obtained and provided to the Seller all
          --------
          consents, approvals or waivers necessary or appropriate for the Buyer
          to enter into this Agreement and to consummate the transactions
          contemplated hereby.  No other authorization, consent, approval,
          license, qualification or formal exemption from, nor any filing,
          declaration or registration with, any court, governmental agency or
          regulatory authority or any securities exchange is required in
          connection with the execution, delivery or performance by the Gothic
          Parties of this Agreement.

     6.3  Litigation. There is no action, suit, investigation or proceeding,
          ----------
          governmental or otherwise, pending or, to the best knowledge of the
          Buyer, threatened to which any of the Gothic Parties is or would be a
          party which seeks to restrain, enjoin, prevent the consummation of or
          otherwise challenge this Agreement or the Buyer's purchase of the
          Option or questions the legality or validity of any such transactions
          or seeks to recover damages or obtain other relief in connection with
          any such transactions.

7.   Default; Failure of Conditions.  In the event either party fails to perform
     ------------------------------
such party's obligations hereunder (except as excused by another party's
default) (the "Defaulting Party") such failure will constitute an event of
default under this Agreement and the other party (the "Other Party") will have
the right to exercise any and all remedies available at law or in equity unless
such default is waived by the Other Party or cured by the Defaulting Party
within five (5) business days after receipt of notice of such default.  The
remedies provided by this Agreement are cumulative and will not exclude any
other remedy to which the Other Party might be entitled under this Agreement or
applicable law.  In the event the Other Party elects to selectively and
successfully enforce the Other Party's rights under this Agreement, such action
will not be deemed a waiver or discharge of any other remedy.  During the
pendency of any default or disputes, this Agreement will be deemed to be in full
force.  Notwithstanding anything herein to the contrary, on the occurrence of a
default or other breach of this Agreement by the Buyer, the Seller may terminate
the Option and the Option Agreement in the sole and absolute discretion of the
Seller.

8.   Standstill.  Each of the parties irrevocably agree that the negotiation,
     ----------
preparation, execution and delivery of this Agreement and any preliminary
discussions with any person regarding this Agreement, the Option or any similar
transaction will not and did not violate any standstill, nonsolicitation or
similar agreement including, without implied limitation, paragraph 5.4 of the
Securities Purchase Agreement among the Buyer, Chesapeake Acquisition
Corporation and Chesapeake Gothic Corp. dated March 31, 1998 (the "Securities
Purchase Agreement"), and relating to the purchase of the GEC Securities by
affiliates of the Seller.  The Buyer hereby releases, acquits and forever
discharges the CEC Parties and the CEC Parties' directors, officers,
shareholders, partners, members, employees, agents, attorneys, parent
corporations, subsidiary corporations, affiliates and such parties' respective
successors and assigns from any and all claims, whether asserted or assertable,
known or unknown, and all actions, debts, suits, causes of action, both at law
and in equity, demands, defenses, offsets, liabilities, losses, obligations or
damages directly or indirectly related to any violation or alleged violation of
the Securities Purchase Agreement arising out of any action, inaction, contact,
discussions or matter prior to the date of this Agreement including, without
implied limitation, any violation or alleged violation of any standstill or
confidentiality agreement set forth in the Securities Purchase Agreement or
otherwise.

9.   Deferral of Operations Turnovers.   Notwithstanding anything to the
     --------------------------------
contrary in this Agreement or in the Participation Agreement, during the
Condition Satisfaction Period, the Seller will not be required to turnover

                                      -4-
<PAGE>

operations on any wells located in the areas described in paragraph 2.1 of this
Agreement including, without limitation, the Della 1-9 well.

10.  Miscellaneous.  It is further agreed as follows:
     -------------

     10.1  Time.  Time is of the essence of this Agreement.
           ----

     10.2  Notices.  Any notice, demand or communication required or permitted
           -------
           to be given by any provision of this Agreement will be in writing and
           will be deemed to have been given and received when delivered
           personally or by telefacsimile to the party designated to receive
           such notice, or on the date following the day sent by overnight
           courier, or on the third (3rd) business day after the same is sent by
           certified mail, postage and charges prepaid, directed to the
           following addresses or to such other or additional addresses as any
           party might designate by written notice to the other parties:

           To the Buyer:            Gothic Energy Corporation
                                    6120 South Yale Avenue, Suite 1200
                                    Tulsa, Oklahoma 74136
                                    Attn: Michael K. Paulk
                                    Telephone (918) 749-5666
                                    Fax No. (918) 749-5882

           With a copy to:      Pray, Walker, Jackman, Williamson & Marlar
                                    900 OneOk Plaza
                                    100 West 5th Street
                                    Tulsa, Oklahoma 74103-4218
                                    Attn: Ira L. Edwards, Jr.
                                    Telephone (918) 581-5500
                                    Fax No. (918) 581-5599

           To the Seller:           Chesapeake Energy Corporation
                                    6100 North Western Avenue
                                    Oklahoma City, Oklahoma 73118
                                    Attn: Aubrey K. McClendon
                                    Telephone (405) 879-9226
                                    Fax No. (405) 848-8588

           With a copy to:      Self, Giddens & Lees, Inc.
                                    2725 Oklahoma Tower
                                    210 Park Avenue
                                    Oklahoma City, Oklahoma 73102
                                    Attn:  Ray Lees
                                    Telephone (405) 232-3001
                                    Fax: (405) 232-5553

     10.3  Press Release.  Except to the extent required by applicable
           -------------
           disclosure requirements, all press releases relating to this
           Agreement and the transactions contemplated by this Agreement will be
           approved by the Buyer and the Seller prior to dissemination.

     10.4  Choice of Law.  This Agreement will be interpreted, construed and
           -------------
           enforced in accordance with the laws of the State of Oklahoma and
           will be deemed for such purposes to have been made, executed and
           performed in Oklahoma County, Oklahoma. All claims, disputes and
           other matters

                                      -5-
<PAGE>

           in question arising out of or relating to this Agreement will be
           decided by proceedings instituted and litigated in the District Court
           of Oklahoma County, Oklahoma, or the United States District Court for
           the Western District of Oklahoma.

     10.5  Headings.  The paragraph headings contained in this Agreement are for
           --------
           reference purposes only and are not intended to affect in any way the
           meaning or interpretation of this Agreement.

     10.6  No Oral Agreements.  There are no unwritten oral agreements,
           ------------------
           understandings, warranties or representations with respect to the
           subject matter of this Agreement.

     10.7  Assignment.  It is agreed that neither party may assign such party's
           ----------
           rights nor delegate such party's duties under this Agreement without
           the express written consent of the other party to this Agreement.

     10.8  Amendment.  Neither this Agreement, nor any of the provisions hereof
           ---------
           can be changed, waived, discharged or terminated, except by an
           instrument in writing signed by the party against whom enforcement of
           the change, waiver, discharge or termination is sought.

     10.9  Severability.  If any clause or provision of this Agreement is
           ------------
           illegal, invalid or unenforceable under any present or future law,
           the remainder of this Agreement will not be affected thereby. It is
           the intention of the parties that if any such provision is held to be
           illegal, invalid or unenforceable, there will be added in lieu
           thereof a provision as similar in terms to such provisions as is
           possible to cause such provision to be legal, valid and enforceable.

     10.10 Attorney Fees.  If any party institutes an action or proceeding
           -------------
           against any other party relating to the provisions of this Agreement,
           the party to such action or proceeding which does not prevail will
           reimburse the prevailing party therein for the reasonable expenses of
           attorneys' fees and disbursements incurred by the prevailing party.

     10.11 Waiver.  Waiver of performance of any obligation or term contained
           ------
           in this Agreement by any party, or waiver by one party of the other's
           default hereunder must be in writing and will not operate as a waiver
           of performance of any other obligation or term of this Agreement or
           constitute a future waiver of the same obligation or a waiver of any
           future default.

           IN WITNESS WHEREOF, the Seller and the Buyer have executed this
Agreement as of the date first above written.

                              GOTHIC ENERGY CORPORATION, an Oklahoma corporation

                              By
                                -----------------------------------
                                  Michael K. Paulk, President

                              GOTHIC PRODUCTION COMPANY, an Oklahoma corporation

                              By
                                -----------------------------------
                                  Michael K. Paulk, President

                              (jointly and severally referred to herein as the
                               "Buyer")

                                      -6-
<PAGE>

                              CHESAPEAKE EXPLORATION LIMITED PARTNERSHIP, an
                              Oklahoma limited partnership

                                   By: Chesapeake Operating, Inc., General
                                        Partner

                                   By
                                     ------------------------------
                                      Aubrey K. McClendon,
                                      Chief Executive Officer

                              (the "Seller")

                                      -7-
<PAGE>

                               OPTION AGREEMENT
                               ----------------

     THIS AGREEMENT is made this ____ day of __________, 2000, between GOTHIC
ENERGY CORPORATION, an Oklahoma corporation ("GEC"), GOTHIC PRODUCTION COMPANY,
an Oklahoma corporation ("GPC"and, jointly and severally with GEC, "Gothic"),
and CHESAPEAKE EXPLORATION LIMITED PARTNERSHIP, an Oklahoma limited partnership,
successor in interest by merger to Chesapeake Gothic Corp. ("Chesapeake").

                               R E C I T A L S :

     WHEREAS, Chesapeake owns (a) __________________ shares of GEC's Senior
Redeemable Preferred Stock, Series B, $0.05 par value per share, (b) the right
to receive accrued and unpaid dividends on such Preferred Stock payable in kind,
and (c) 2,394,125 shares of GEC's Common Stock, $0.01 par value per share
(collectively, the "GEC Securities");

     WHEREAS, Chesapeake or one or more of the wholly owned subsidiaries of
Chesapeake Energy Corporation (collectively, the "CEC Parties"), and Gothic and
its affiliated entities (collectively, the "Gothic Parties") are parties to that
certain Sale and Participation Agreement dated as of March 31, 1998, as amended
(the "Participation Agreement") pursuant to which:  (a) Chesapeake acquired an
undivided fifty percent (50%) interest in certain oil, gas and related assets
from the Gothic Parties, (b) the CEC Parties and the Gothic Parties provided for
the maintenance, joint development and operation of the Existing Acreage, the
Related Interests and the Acquisition Acreage (as those terms are defined in the
Participation Agreement), and (c) an area of mutual interest was created among
the CEC Parties and the Gothic Parties covering lands located in whole or in
part in the States of Arkansas, Kansas, New Mexico (excluding the Pecos Slope
Acreage), Oklahoma and Texas; and

     WHEREAS, Gothic has purchased an option to acquire all of Chesapeake's GEC
Securities which Chesapeake has granted, such option to be evidenced by and
subject to the terms and conditions set forth in this Agreement.

     NOW, THEREFORE, in consideration of receipt of the consideration set forth
in that certain Option Purchase Agreement of even date herewith, the mutual
covenants herein contained and other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the parties agree as
follows:

1.   Option Agreement. Chesapeake hereby grants to Gothic the right and option
to purchase all of the GEC Securities owned by Chesapeake (the "Option") in
strict accordance with the terms and conditions of this Agreement.

2.   Term. Unless Fully Exercised in strict accordance with all of the terms and
conditions set forth in this Agreement, unless extended in writing by
Chesapeake, the Option will expire on the

Final Schedule    Schedule "A"
--------------
                                                              Page 1 of 17 Pages
<PAGE>

earlier of: (i) __________, 2000, at 5:00 p.m. Oklahoma City, Oklahoma time; or
(ii) thirty (30) days after the confirmation order of the plan of bankruptcy for
Gothic (the "Option Period"), and all rights and obligations of Chesapeake and
the Gothic Parties under this Agreement will expire and terminate without any
further notice or action. The Option will be deemed "Fully Exercised" if, and
only if, each of the following actions is completed before the expiration of the
Option Period: (a) receipt by Chesapeake of the exercise notice under paragraph
of this Agreement; (b) satisfaction in full by the Gothic Parties of all
conditions precedent set forth in this Agreement; and (c) full and complete
performance by the Gothic Parties of the Exercise Consideration (as defined
below) including, without implied limitation, the execution, delivery and
recordation (where appropriate) of the Conveyance Documents and the Restated
Participation Agreement (as those terms are defined below).

3.   Exercise.  Gothic may exercise the Option at any time prior to the
expiration of the Option Period by delivery to Chesapeake of a written notice
advising Chesapeake of Gothic's intent to exercise the Option.  On receipt of
such notice of intent to exercise: (a) this Agreement will be deemed a legally
binding agreement by Gothic to purchase the GEC Securities from Chesapeake prior
to the expiration of the Option Period on the terms and conditions stated in
this Agreement; and (b) this Agreement will be deemed to be a legally binding
agreement by Chesapeake to sell the GEC Securities to Gothic prior to the
expiration of the Option Period under the terms and conditions stated in this
Agreement.  Notwithstanding the foregoing, Chesapeake will have no obligation to
assign or deliver any interest in the GEC Securities to Gothic until the Option
is Fully Exercised.

4.   Exercise Consideration.  The payment of the "Exercise Consideration" means
the performance by Gothic of all of the following agreements in accordance
herewith:

     4.1  Sale and Conveyance. As a portion of the Exercise Consideration the
          Gothic Parties will convey and assign to the CEC Parties all of the
          Gothic Parties' right, title and interest in and to the Properties (as
          defined below) free and clear of any and all liens, claims and
          encumbrances. The Properties assigned to the CEC Parties will be
          assigned pursuant to the form of assignment at Schedule "(a)" attached
          as a part hereof with appropriate schedules attached to describe the
          Properties as set forth in Schedule "4.1(b)" attached hereto as a part
          hereof (the "Property Schedules") and the Properties located within
          the CHK Area (as hereinafter defined) will be released from the terms
          of the Participation Agreement in all respects.

     4.2  Participation Agreement. The Gothic Parties and the CEC Parties will
          enter into the Amended and Restated Participation Agreement in the
          form of Schedule "" attached as a part hereof (the "Restated
          Participation Agreement") which will amend and replace the
          Participation Agreement to the extent set forth in the Restated
          Participation Agreement.

     4.3  Definitions. For purposes of this Agreement the term "Properties"
          means the following: (a) any right to any reconveyance in favor of the
          Gothic Parties under

Final Schedule    Schedule "A"
--------------
                                                              Page 2 of 17 Pages
<PAGE>

          paragraph 1.3 of the Participation Agreement, any reversion or any
          other interest owned by the Gothic Parties under the Participation
          Agreement in the fifty percent (50%) interest in the Existing Acreage,
          the Related Interests and the Acquisition Acreage (as those terms are
          defined in the Participation Agreement) previously conveyed to the CEC
          Parties together with any related interests or property rights
          acquired by the CEC Parties so that the CEC Parties own such interest
          in any and all acreage, interests and property rights acquired in
          connection with the Participation Agreement free and clear of all re-
          assignment obligations, reversionary interests or any other terms or
          obligations under the Participation Agreement; (b) except for the
          Gothic Wellbore Interests (as defined below) but specifically
          including any other wells participated in by the Gothic Parties
          pursuant to paragraph 5.8 of this Agreement, all of the Gothic
          Parties' right, title and interest in all oil, gas and mineral
          interests of every kind and character within the CHK Area (as defined
          below) together with any related interests and property rights
          including, without limitation, any interest in farmout agreements,
          contribution agreements, exploration agreements, access agreements,
          the Existing Acreage, the Related Interests, the Acquisition Acreage
          and other agreements to acquire such interests which are owned by the
          Gothic Parties in the CHK Area; and (c) the right to operations of all
          wells in the CHK Area including, without limitation, any well
          containing the Gothic Wellbore Interests. For purposes of this
          Agreement: (y) the term "CHK Area" means: (i) Meade and Clark
          Counties, Kansas, and (ii) Texas, Beaver, Harper, Ellis, Woods,
          Woodward, Dewey, Major, Blaine (Townships in 19N only), Custer, Grady
          (Townships in 7N, 8N and 9N only), Pittsburg, Haskell, Latimer
          (excluding Sections 25, 34, 35 and 36 in Township 3 North, Range 19
          East, Sections19, 22, 23, 24, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35
          and 36 in Township 3 North, Range 20 East and Sections 19, 20, 27, 28,
          31, 32, 33, and 34 in Township 3 North, Range 21 East) and LeFlore
          Counties, Oklahoma; and (z) the term "Gothic Wellbore Interests" means
          the Gothic Parties' interests in the following wellbores (but
          excluding any interest in any acreage within the applicable
          governmental production unit): (i) any wellbores in the CHK Area which
          were producing in paying quantities as of February 1, 2000, and (ii)
          the next wellbores to be drilled in the designated quarter section of
          the governmental spacing units as described in Schedule "4.3" attached
          hereto as a part hereof which includes four (4) locations in Custer
          County, Oklahoma, six (6) locations in Pittsburg County, Oklahoma,
          four (4) locations in Latimer County, Oklahoma and one (1) location in
          Major County, Oklahoma.

5.   Conditions Precedent to Exercise.  Unless waived in writing by Chesapeake
in Chesapeake's sole discretion, the right of Gothic to exercise the Option is
subject to the satisfaction of all of the following conditions precedent:

     5.1  Plan of Reorganization. A plan of reorganization for Gothic will have
          been confirmed under the United States Bankruptcy Code, as amended, on
          terms and conditions which approve, without modification, this
          Agreement, the Restated Participation Agreement and all of the other
          instruments, agreements,

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<PAGE>

conveyances, certificates, memoranda and other documents to be entered into upon
the exercise of the Option and the consummation of the provisions of this
Agreement (the "Conveyance Documents").

     5.2  Approvals. Chesapeake and Gothic will have received written consents
          and approvals to the terms and conditions of this Agreement and the
          Conveyance Documents in form and substance satisfactory to Chesapeake
          from the holders of the Gothic's 14 1/8% Senior Secured Discount
          Notes, the holders of the Gothic's Senior Notes, Bank One, Texas,
          N.A., and any other necessary parties deemed necessary or prudent by
          Chesapeake.

     5.3  Lien Releases. Chesapeake will have received lien releases and other
          documents required to assure Chesapeake that the Properties and the
          other interests to be acquired by the CEC Parties under the Conveyance
          Documents will be free and clear of all liens, claims and
          encumbrances.

     5.4  Conveyance Documents. The Conveyance Documents will have been duly
          executed, acknowledged (where appropriate) and delivered by the Gothic
          Parties and the CEC Parties, the Conveyance Documents will include a
          certificate making and reaffirming each of the representations,
          warranties, covenants and agreements set forth in this Agreement, and
          the covenants and conditions precedent set forth therein will have
          been satisfied.

     5.5  Litigation. No actions, suits or litigation will have been threatened
          or filed seeking to prevent the consummation of the transactions
          contemplated by the Conveyance Documents or seeking damages or other
          relief as a result of the Conveyance Documents or the consummation of
          the transactions contemplated thereby and: (a) no preliminary or
          permanent injunction or other order will have been issued by any court
          of competent jurisdiction or any regulatory body preventing
          consummation of the transactions contemplated by this Agreement or the
          Conveyance Documents; (b) no action will have been commenced or
          threatened against Chesapeake, Gothic or any of their respective
          affiliates, associates, officers or directors seeking damages arising
          from, to prevent or challenge the transactions contemplated by this
          Agreement and the Conveyance Documents; (c) all representations and
          warranties of Gothic contained herein will be true and correct in all
          material respects on and as of the date of the exercise of the Option;
          and (d) the Gothic Parties will have performed or satisfied on and as
          of the date of the exercise of the Option, all obligations, covenants,
          agreements and conditions contained in this Agreement and the
          Conveyance Documents to be performed or complied with by the Gothic
          Parties.

     5.6  Lease Maintenance. The Gothic Parties will have maintained in full
          force and effect all of the oil, gas and mineral leases, farmout
          agreements, joint development agreements, joint operating agreements
          and other oil and gas related

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<PAGE>

          interests covered by the Participation Agreement in full force and
          effect and will not have rejected or terminated any of such interests
          or breached any of the terms or conditions applicable thereto.

     5.7  No Default. The Gothic Parties will have not defaulted under this
          Agreement, the Participation Agreement or the Option Purchase
          Agreement, each of the Gothic Parties' representations and warranties
          will be true and correct in all material respects and there will not
          have occurred any event that would constitute an event of default with
          the passage of time.

     5.8  Participation. The Gothic Parties will not have proposed any wells to
          be drilled in or on any governmental production unit (as defined in
          the Participation Agreement) containing any of the Properties in the
          CHK Area as to which drilling operations had not commenced prior to
          February 1, 2000 and, with respect to any wells (other than the Gothic
          Wellbore Interests) proposed by the Chesapeake Parties or third
          parties spudded after February 1, 2000 ("Interim Wells"), in the event
          the Gothic Parties elect to participate therein, all of the interests
          of the Gothic Parties in such Interim Wells and the governmental
          spacing units with respect thereto will, at Chesapeake's election, be
          included in the Properties to be conveyed to Chesapeake pursuant to
          paragraph 10.2.1 of this Agreement. In the event the Gothic Parties
          elect not to participate in any such Interim Wells, the Gothic Parties
          will have farmed out, assigned or otherwise conveyed to the Chesapeake
          Parties, the Gothic Parties' interests in any such Interim Wells and
          the governmental spacing units pursuant to the Participation
          Agreement.

     5.9  JIB Payments. The Gothic Parties will have paid current all joint
          interest billings owing to the CEC Parties as required by the Joint
          Operating Agreements attached to the Participation Agreement.

     5.10 Motion to Affirm. Within forty-five (45) days after the filing of the
          petition in bankruptcy for one or more of the Gothic Parties, the
          Gothic Parties will have filed a motion and will thereafter diligently
          pursue entry of an order in such bankruptcy proceeding to irrevocably
          affirm this Agreement, the Option, the Conveyance Documents, the
          Participation Agreement and the Restated Participation Agreement in
          all respects.

6.   Chesapeake Representations and Warranties.  Chesapeake hereby represents
and warrants to Gothic that as of the date of this Agreement and until the
Option is exercised in accordance with the terms and conditions of this
Agreement or the Option Period has expired without the Option being exercised:

     6.1  Ownership. Chesapeake has and will have good and valid title to the
          GEC Securities, free and clear of all liens, claims and encumbrances.
          No person or entity other than the CEC Parties has or will have any
          interest in the GEC

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<PAGE>

          Securities either of record or beneficially.

     6.2  Authority. Chesapeake has taken all necessary action to authorize the
          execution, delivery and performance of this Agreement and has adequate
          corporate power, authority and legal right to enter into, execute,
          deliver and perform this Agreement and to consummate the transactions
          contemplated hereby.

     6.3  Absence of Liabilities. Except as approved by Gothic in writing prior
          to the Closing Date: (a) Chesapeake has no debt, liability, obligation
          or commitment, absolute or contingent, known or unknown, relating to
          or connected with the GEC Securities; (b) the GEC Securities will not
          be subject to or liable for any claim, debt, liability, lien,
          encumbrance, obligation, guaranty or commitment of Chesapeake on the
          Closing Date; and (c) any such claims, debts, liabilities, obligations
          or commitments will be the sole responsibility of Chesapeake and
          Chesapeake hereby agrees to indemnify and hold harmless Gothic from
          all such matters.

     6.4  Consents and Approvals. No notice to, filing with, or authorization,
          consent or approval of any governmental entity, person or other entity
          is necessary for the consummation of the transactions contemplated by
          this Agreement. The execution, delivery, performance and consummation
          of this Agreement does not and will not: (a) violate, conflict with or
          constitute a default or an event that, with notice or lapse of time or
          both, would be a default, breach or violation under any term or
          provision of any instrument, agreement, contract, commitment, license,
          promissory note, conditional sales contract, indenture, mortgage, deed
          of trust, lease or other agreement, instrument or arrangement to which
          Chesapeake is a party or by which Chesapeake or, to the best of
          Chesapeake's knowledge, the GEC Securities are bound; (b) violate,
          conflict or constitute a breach of any statute, regulation or judicial
          or administrative order, award, judgment or decree to which Chesapeake
          is a party or to which Chesapeake or, to the best of Chesapeake's
          knowledge the GEC Securities are bound; or (c) result in the creation
          or imposition of any adverse claim or interest, lien, encumbrance,
          charge, equity or restriction of any nature whatever, upon or
          affecting Chesapeake, or to the best of Chesapeake's knowledge, the
          GEC Securities or Gothic.

7    Gothic Representations and Warranties. Gothic hereby represents and
warrants to Chesapeake that as of the date of this Agreement and as of the
Closing Date:

     7.1  Authority and Reliance. Gothic has taken all necessary action to
          authorize the execution, delivery and performance of this Agreement
          and has all requisite corporate power, authority and legal right to
          enter into, execute, deliver and perform this Agreement and to
          consummate the transactions contemplated hereby and to own, lease, and
          operate its properties and to conduct its business as now being
          conducted. Gothic represents and warrants that Gothic is experienced
          in the

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<PAGE>

          oil and gas business and has knowledge and experience in business and
          financial matters and, with respect to investments generally and, in
          particular, investments generally comparable to the Option and the GEC
          Securities, Gothic is competent to evaluate the value of each of the
          GEC Securities and the Exercise Price and the benefits and risks
          relating to this Agreement and Gothic has determined that the
          consideration being given by Gothic is the fair value equivalent of
          the consideration being received by Gothic for the purchase and
          exercise of the Option. If Gothic exercises the Option, Gothic's
          representations and warranties hereunder will extend fully to the
          exercise of the Option as if made on the date the Option is exercised.

     7.2  Consents. Gothic has obtained and provided to Chesapeake all consents,
          approvals or waivers necessary or appropriate for Gothic to enter into
          this Agreement and to consummate the transactions contemplated hereby.
          No other authorization, consent, approval, license, qualification or
          formal exemption from, nor any filing, declaration or registration
          with, any court, governmental agency or regulatory authority or any
          securities exchange is required in connection with the execution,
          delivery or performance by the Gothic Parties of this Agreement.

     7.3  Litigation. There is no action, suit, investigation or proceeding,
          governmental or otherwise, pending or, to the best of Gothic's
          knowledge, threatened to which any of the Gothic Parties is or would
          be a party or of which the Properties, the Properties or other assets
          of the Gothic Parties is or would be subject.

     7.4  Properties. All of the oil, gas and related interests of every kind
          and character owned by the Gothic Parties or any of the Gothic
          Parties' direct or indirect subsidiaries which are located in the CHK
          Area are described in Schedule "7.4" attached as a part hereof.

8.   Covenants.  Unless waived in writing, the parties agree to the following
during the Option Period:

     8.1  Conduct of Businesses. Prior to the exercise of the Option or
          expiration of the Option Period, the Gothic Parties will operate in a
          businesslike manner in accordance with prior practices and will
          maintain and preserve all of the assets and businesses of the Gothic
          Parties including the Properties.

     8.2  Properties. The Gothic Parties have not and will not: (a) transfer,
          sell, mortgage, pledge, encumber or dispose of any assets covered by
          this Agreement or the Restated Participation Agreement, except for the
          existing mortgages which have been subordinated to the interests of
          Chesapeake pursuant to the Participation Agreement; or (b) except in
          the ordinary course of business consistent with past business
          practices, make or permit any amendment or termination of any material
          contract, agreement or commitment affecting the assets covered by this

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<PAGE>

          Agreement or the Restated Participation Agreement.

     8.3  Consents. The parties will use their best efforts to obtain, all
          licenses, permits, consents, approvals, authorizations, qualifications
          and orders of governmental authorities and parties to contracts with
          the Gothic Parties as are necessary for the consummation of the
          transactions contemplated by this Agreement or are reasonably
          requested by Chesapeake.

     8.4  Litigation. Promptly on learning thereof, each party to this Agreement
          will notify the other party of any litigation, suit or administrative
          proceeding that could reasonably be expected to have a material
          adverse affect on the ability of the parties to consummate the
          transactions contemplated by this Agreement or the Conveyance
          Documents, or otherwise adversely affect any of the businesses,
          affairs, assets, prospects, operations or conditions, financial or
          otherwise, of the parties, whether or not the claim is considered to
          be covered by insurance. Gothic and Chesapeake each agree to not to
          agree to or join in the pursuit of any injunctive relief prohibiting
          the transactions contemplated by this Agreement.

     8.5  Plan of Reorganization. Gothic will not propose or consent to any plan
          of reorganization which materially conflicts with any of the terms and
          conditions of this Agreement, the Conveyance Documents or the Restated
          Participation Agreement and will not dispute or seek to modify or
          rescind this Agreement in any bankruptcy proceeding or other action
          affecting Gothic. The Gothic Parties will simultaneously provide to
          Chesapeake copies of all notices, filings and other documents relating
          to the Gothic Parties bankruptcy, reorganization or any proposed plan
          of reorganization including, without limitation, all communications
          to, from or among any of the Gothic Parties, any formal or informal
          committees of creditors or security holders or any creditors of the
          Gothic Parties, whether before or after the filing of bankruptcy.

     8.6  GEC Securities. Chesapeake will not transfer, sell, pledge, encumber
          or dispose of any of the GEC Securities.

9.   Representations and Warranties for the Properties.  As an inducement to
Chesapeake to enter into this Agreement and accept the assignment of the
interests in the Properties, Gothic represents and warrants to Chesapeake that
as of the date of this Agreement and the Closing Date:

     9.1  No Assumption of Obligations. Except as approved by Chesapeake in
          writing prior to the Closing Date, the execution and consummation of
          this Agreement will not obligate Chesapeake with respect to (or result
          in the assumption by Chesapeake of) any obligation of Gothic arising
          prior to the Closing Date under or with respect to, any liability,
          agreement or commitment relating to the Properties including, without
          implied limitation, to pay to or share with any third

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<PAGE>

          party any portion of the Hydrocarbons attributable to the Properties.
          The term "Hydrocarbons" means and includes oil, gas, casinghead gas,
          condensate, natural gas liquids and all components of the foregoing.

     9.2  Absence of Liabilities. Except as approved by Chesapeake in writing
          prior to the Closing Date: (a) Gothic has no debt, liability,
          obligation or commitment, absolute or contingent, known or unknown,
          relating to or connected with the Properties; (b) neither Chesapeake
          nor the Properties will be subject to or liable for any claim, debt,
          liability, lien, encumbrance, obligation, guaranty or commitment on
          the Closing Date; and (c) any such claims, debts, liabilities,
          obligations or commitments will be the sole responsibility of Gothic
          and Gothic hereby agrees to indemnify and hold harmless Chesapeake
          from all such matters. Gothic has complied and will continue to comply
          with all applicable federal, state or local statutes, laws and
          regulations.

     9.3  Contracts. Gothic has delivered to Chesapeake true copies (or
          descriptions, in the case of oral agreements) of all of the contracts
          and agreements relating to the Properties including, without
          limitation, all marketing and production sales contracts. Except as
          approved by Chesapeake in writing prior to the Closing Date, no such
          marketing or production sales contracts will in any way prevent or
          hinder Chesapeake in taking in kind Chesapeake's share of production
          from the Properties. There are no other material contracts,
          commitments or agreements in effect related to the Properties that
          have not been disclosed to Chesapeake in writing. To the best of
          Gothic's knowledge: (a) such contracts and agreements are in full
          force and effect; (b) no event of default or event which would become
          an event of default with the giving of notice or passage of time has
          occurred; and (c) no condition presently exists which would give any
          party to any such contract the right to terminate such contract. There
          are no other material contracts, commitments or agreements in effect
          related to the Properties.

     9.4  Consents and Approvals. No notice to, filing with, or authorization,
          consent or approval of any governmental entity, person or other entity
          is necessary for the consummation of the transactions contemplated by
          this Agreement. The execution, delivery, performance and consummation
          of this Agreement does not and will not: violate, conflict with or
          constitute a default or an event that, with notice or lapse of time or
          both, would be a default, breach or violation under any term or
          provision of any instrument, agreement, contract, commitment, license,
          promissory note, conditional sales contract, indenture, mortgage, deed
          of trust, lease or other agreement, instrument or arrangement to which
          Gothic is a party or by which Gothic or, to the best of Gothic's
          knowledge, the Properties are bound; violate, conflict or constitute a
          breach of any statute, regulation or judicial or administrative order,
          award, judgment or decree to which Gothic is a party or to which
          Gothic or, to the best of Gothic's knowledge the Properties are bound;
          or result in the creation or imposition of any adverse claim or
          interest, lien,

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<PAGE>

          encumbrance, charge, equity or restriction of any nature whatever,
          upon or affecting Gothic, or to the best of Gothic's knowledge, the
          Properties or Chesapeake.

     9.5  Litigation. To the best of Gothic's knowledge there is: (a) no action,
          suit or proceeding pending, threatened or contemplated against Gothic
          or the Properties; and (b) no proceeding, investigation, charge, audit
          or inquiry threatened or pending before or by any federal, state,
          municipal or other governmental court, department, commission, board,
          bureau, agency or instrumentality which might result in an adverse
          effect on Gothic or the Properties. Gothic hereby agrees to indemnify
          and hold harmless Chesapeake with respect to any and all litigation
          and proceedings.

     9.6  Title. Gothic owns, possesses and holds good and defensible title
          beneficially and of record in and to the respective Properties free
          and clear of all claims, liens, encumbrances, conditions,
          restrictions, calls on production, obligations to pay to or share with
          third parties any revenue or other matter adversely affecting the
          value or ownership of the Properties. All of the oil, gas and related
          interests of every kind and character owned by Gothic or any of
          Gothic's affiliates which are located in the CHK Area are described in
          the Conveyance Documents. Gothic is entitled to receive not less than
          the "Net Revenue Interest" set forth in the Conveyance Documents of
          all Hydrocarbons produced, saved and marketed from the Properties
          without reduction, suspension or termination of such interest
          throughout the duration of the productive life of such Properties and
          is in no event obligated to bear any of the costs and expenses related
          to the maintenance, development or operation (including, without
          limitation, the costs and expenses of plugging and abandoning any
          wells and removal and salvage of any equipment and facilities) of the
          Properties throughout the productive life of the Properties in excess
          of the "Working Interest" set forth in Conveyance Documents. To the
          best of Gothic's knowledge, there are no suspended revenues or any
          basis to suspend revenues from the Properties. To the best of Gothic's
          knowledge, there does not exist any lien, claim, encumbrance,
          restriction or other matter which might cause Chesapeake to not
          receive for its own account free and clear of all liens, claims and
          encumbrances the percentage of the fair market value of all
          Hydrocarbons produced, saved or used from each of the Properties after
          the Closing Date equal to the Net Revenue Interest designated in the
          Conveyance Documents.

     9.7  Foreign Person. Gothic is not a "foreign person" as that term is
          defined under the Internal Revenue Code of 1986.

     9.8  Oil and Gas Leases in Good Standing. Except as approved by Chesapeake
          in writing prior to the Closing Date, to the best of Gothic's
          knowledge all oil and gas leases which are material singly or in the
          aggregate are in full force and effect, and Gothic is not in default
          thereunder.

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<PAGE>

     9.9   Taxes. All ad valorem, property, production, severance and similar
           taxes and assessments based on or measured by the ownership of
           property comprising the Properties or the production or removal of
           hydrocarbons or the receipt of proceeds therefrom have been timely
           paid when due and are not in arrears.

     9.10  Contracts, Consents and Preferential Rights. Gothic has disclosed to
           Chesapeake in writing after the date hereof by reference to this
           paragraph: (a) all partnership, joint venture, farmin/farmout, dry
           hole, bottom hole, acreage contribution, area of mutual interest,
           purchase and/or acquisition agreements of which any terms remain
           executory which materially affect the Properties; (b) all other
           executory contracts to which Gothic is a party which materially
           affect any item of the Properties; (c) all governmental or court
           approvals and third party contractual consents required in order to
           consummate the transactions contemplated by this Agreement; (d) all
           agreements pursuant to which third parties have preferential rights
           or similar rights to acquire any portion of the Properties upon the
           sale contemplated by this Agreement; and (e) all other contracts and
           agreements which are in any single case of material importance to the
           Properties.

     9.11  Tax Partnerships. None of the Properties is treated for income tax
           purposes as being owned by a partnership.

     9.12  Environmental Conditions. Gothic is not aware, and has not received
           notice from any person, entity or governmental body, agency or
           commission, of any release, disposal, event, condition, circumstance,
           activity, practice or incident concerning any land, facility, asset
           or property that: (a) interferes with or prevents compliance or
           continued compliance by Gothic (or by Chesapeake after the Closing
           Date) with any federal, state or local law, regulation, code or
           ordinance or the terms of any license or permit issued pursuant
           thereto; or (b) gives rise to or results in any common law or other
           liability of Gothic to any person, entity or governmental body,
           agency or commission for damage or injury to natural resources,
           wildlife, human health or the environment which would have a material
           adverse effect on Gothic in each case. Gothic is not aware of any
           civil, criminal or administrative action, lawsuit, demand,
           litigation, claim, hearing, notice of violation, investigation or
           proceeding, pending or threatened, against Gothic or operator of any
           of the lands, facilities, assets and properties owned or formerly
           owned, operated, leased or used by Gothic as a result of the
           violation or breach of any federal, state, or local law, regulation,
           code or ordinance or any duty arising at common law to any person,
           entity or governmental body, singly or in the aggregate, which if
           determined adversely would have a material adverse effect on Gothic.

     9.13  Plugging Status. To the best of Gothic's knowledge, all wells on the
           Properties that have been permanently plugged and abandoned have been
           so plugged and

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<PAGE>

           abandoned in accordance in all material respects with all applicable
           requirements of each governmental authority having jurisdiction over
           Gothic and the Properties.

     9.14  Affiliate Transactions. There are no transactions affecting any of
           the Properties between Gothic and any of Gothic's affiliates. As used
           in this Agreement, "affiliate" means, with respect to any person or
           entity, each other person or entity directly or indirectly
           controlling controlled by or under common control with such person.

     9.15  Full Disclosure. This Agreement, any schedule referenced in or
           attached to this Agreement, any document furnished to Chesapeake
           under this Agreement and any certification furnished to Chesapeake
           under this Agreement does not contain any untrue statement of a
           material fact and does not omit to state a material fact necessary to
           make the statements made, in the circumstances under which they were
           made, not misleading. All of the representations, warranties and
           covenants in this Agreement: (a) are true and correct as of the date
           made; (b) will be true and correct as of the Closing Date; and (c)
           will survive and not be waived, discharged, released, modified,
           terminated or affected by any due diligence by Chesapeake.

10.  Closing.  Unless the Option Period has expired or the closing is extended
in writing by Gothic and Chesapeake, the transactions contemplated by this
Agreement will be consummated on the date (the "Closing Date") which is five (5)
business days after the later of: (a) the notice of intent to exercise under
paragraph  of this Agreement; or (b) the date all of the conditions under this
Agreement have been satisfied in full.

     10.1  Chesapeake's Deliveries. Subject to the terms and conditions of this
           Agreement, on the Closing Date Chesapeake will deliver or cause to be
           delivered to Gothic the following items (all documents will be duly
           executed and acknowledged where required):

           10.1.1   GEC Securities. Conditioned on the Option being Fully
                    Exercised, the GEC Securities due under paragraph of this
                    Agreement together with stock powers with all signatures
                    guaranteed in the form attached hereto as Schedule "10.1.1";

           10.1.2   Evidence of Authority. Such resolutions, certificates of
                    good standing, incumbency certificates and other evidence of
                    authority with respect to Chesapeake as might be reasonably
                    requested by Gothic;

           10.1.3   JIB Payments. Current payment of all joint interest billings
                    owing to the Gothic Parties as required by the Joint
                    Operating Agreements attached to the Participation
                    Agreement;

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           10.1.4   Closing Memorandum. A memorandum setting forth the items
                    delivered and accounting for the payments made on the
                    Closing Date;

           10.1.5   Additional Documents. Such additional documents as might be
                    reasonably requested by Gothic to consummate this Agreement;
                    and

           10.1.6   Interim Wells. In the event Chesapeake elects to include the
                    Gothic Parties' interests in the Interim Wells in the
                    Properties pursuant to paragraph 5.8 hereof, Chesapeake will
                    pay to the Gothic Parties an amount equal to the Gothic
                    Parties' unrecovered drilling costs for such Interim Wells.

     10.2  Gothic's Deliveries. On the Closing Date, Gothic will deliver or
           cause to be delivered to Chesapeake the following items (all
           documents will be duly executed and acknowledged where required):

           10.2.1   Assignments. The Conveyance Documents in substantially the
                    form and substance satisfactory to Chesapeake conveying to
                    Chesapeake all of Gothic Parties' right, title and interest
                    in and to the Properties including, without limitation, all
                    of the right, title and interest in and to the Interim Wells
                    in the event Chesapeake elects to include the Interim Wells
                    in the Properties pursuant to paragraph 5.8 hereof;

           10.2.2   Releases. Releases and termination statements with respect
                    to any and all liens, claims, security interests and other
                    encumbrances covering any of the Properties including a
                    release of any reconveyance rights in favor of the Gothic
                    Parties under the Participation Agreement;

           10.2.3   Evidence of Authority. Such corporate resolutions,
                    certificates of good standing, incumbency certificates and
                    other evidence of authority with respect to each of the
                    Gothic Parties as might be reasonably requested by
                    Chesapeake;

           10.2.4   Closing Memorandum. A memorandum setting forth the items
                    delivered and accounting for the payments made on the
                    Closing Date;

           10.2.5   Additional Documents. Such additional documents as might be
                    reasonably requested by Chesapeake to consummate this
                    Agreement.

     10.3  Costs. Gothic will pay the following closing costs: (a) Gothic's
           attorneys' fees, investment banker's fees and bank fees; (b) the cost
           of recording all mortgage or other lien releases and the cost of
           documentary stamps to be affixed to any deeds conveying title to the
           Properties to Chesapeake; and (c) any other charge imposed by any
           governmental authority for the transfer of any item comprising the

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           Properties. Chesapeake will pay only Chesapeake's attorneys' fees and
           the cost of recording the Conveyance Documents. Chesapeake and the
           Gothic Parties each agree to use their respective best efforts to
           take any and all reasonable action to minimize the recording costs
           and other charges associated with the consummation of the
           transactions contemplated by this Agreement.

     10.4  Files and Data. As of the Closing Date and at all times thereafter
           during the term of the Restated Participation Agreement, Gothic will
           make available to Chesapeake for copying, at Chesapeake's expense,
           all files, records, reports and other data relating to the
           Properties.

11.  Default.  In the event either party fails to perform such party's
obligations hereunder (except as excused by another party's default) (the
"Defaulting Party") such failure will constitute an event of default under this
Agreement and the other party (the "Other Party") will have the right to
exercise any and all remedies available at law or in equity including, without
limitation, specific performance of this Agreement or any one or more of the
provisions herein contained, unless such default is waived by the Other Party or
cured by the Defaulting Party within five (5) business days after receipt of
notice of such default.  The remedies provided by this Agreement are cumulative
and will not exclude any other remedy to which the Other Party might be entitled
under this Agreement or applicable law.  In the event the Other Party elects to
selectively and successfully enforce the Other Party's rights under this
Agreement, such action will not be deemed a waiver or discharge of any other
remedy.  During the pendency of any default or disputes, this Agreement will be
deemed to be in full force and effect.  Notwithstanding anything herein to the
contrary, on the occurrence of a default or other breach of this Agreement by
Gothic, Chesapeake may terminate the Option in the sole and absolute discretion
of Chesapeake.

12.  Miscellaneous.  It is further agreed as follows:

     12.1  Time.  Time is of the essence of this Agreement.

     12.2  Notices. Any notice, demand or communication required or permitted to
           be given by any provision of this Agreement will be in writing and
           will be deemed to have been given and received when delivered
           personally or by telefacsimile to the party designated to receive
           such notice, or on the date following the day sent by overnight
           courier, or on the third (3rd) business day after the same is sent by
           certified mail, postage and charges prepaid, directed to the
           following addresses or to such other or additional addresses as any
           party might designate by written notice to the other parties:

Final Schedule    Schedule "A"
--------------
                                                          Page 14 of 17 Pages
<PAGE>

           To Gothic:               Gothic Energy Corporation
                                    6120 South Yale Avenue, Suite 1200
                                    Tulsa, Oklahoma 74136
                                    Attn: Michael K. Paulk
                                    Telephone (918) 749-5666
                                    Fax No. (918) 749-5882

           With a copy to:          Pray, Walker, Jackman, Williamson & Marlar
                                    900 OneOk Plaza
                                    100 West 5th Street
                                    Tulsa, Oklahoma 74103-4218
                                    Attn: Ira L. Edwards, Jr.
                                    Telephone (918) 581-5500
                                    Fax No. (918) 581-5599

           To Chesapeake:           Chesapeake Energy Corporation
                                    6100 North Western Avenue
                                    Oklahoma City, Oklahoma 73118
                                    Attn: Aubrey K. McClendon
                                    Telephone (405) 879-9226
                                    Fax No. (405) 848-8588

           With a copy to:          Self, Giddens & Lees, Inc.
                                    2725 Oklahoma Tower
                                    210 Park Avenue
                                    Oklahoma City, Oklahoma 73102
                                    Attn: Ray Lees
                                    Telephone (405) 232-3001
                                    Fax: (405) 232-5553

     12.3  Cooperation. At all times during the Option Period the parties agree
           to execute and deliver, or cause to be executed and delivered, such
           documents and do, or cause to be done, such other acts and things as
           might reasonably be requested by the other party to this Agreement to
           assure that the benefits of this Agreement are realized by the
           parties.

     12.4  Press Release. Except to the extent required by applicable disclosure
           requirements, all press releases relating to this Agreement and the
           transactions contemplated by this Agreement and the Conveyance
           Documents will be approved by Gothic and Chesapeake prior to
           dissemination.

     12.5  Choice of Law. This Agreement will be interpreted, construed and
           enforced in accordance with the laws of the State of Oklahoma and
           will be deemed for such

Final Schedule    Schedule "A"
--------------
                                                         Page 15 of 17 Pages
<PAGE>

            purposes to have been made, executed and performed in Oklahoma
            County, Oklahoma. All claims, disputes and other matters in question
            arising out of or relating to this Agreement will be decided by
            proceedings instituted and litigated in the District Court of
            Oklahoma County, Oklahoma or the United States District Court for
            the Western District of Oklahoma.

     12.6   Headings. The paragraph headings contained in this Agreement are for
            reference purposes only and are not intended to affect in any way
            the meaning or interpretation of this Agreement.

     12.7   Entire Agreement. This Agreement and any document executed in
            connection herewith on or after the date of this Agreement
            constitute the entire agreement between the parties with respect to
            the subject matter hereof and there are no agreements,
            understandings, warranties or representations except as set forth
            herein.

     12.8   Assignment. It is agreed that the parties may not assign such
            party's rights nor delegate such party's duties under this Agreement
            without the express written consent of the other parties to this
            Agreement.

     12.9   Amendment. Neither this Agreement, nor any of the provisions hereof
            can be changed, waived, discharged or terminated, except by an
            instrument in writing signed by the party against whom enforcement
            of the change, waiver, discharge or termination is sought.

     12.10  Severability. If any clause or provision of this Agreement is
            illegal, invalid or unenforceable under any present or future law,
            the remainder of this Agreement will not be affected thereby. It is
            the intention of the parties that if any such provision is held to
            be illegal, invalid or unenforceable, there will be added in lieu
            thereof a provision as similar in terms to such provisions as is
            possible to cause such provision to be legal, valid and enforceable.

     12.11  Attorney Fees. If any party institutes an action or proceeding
            against any other party relating to the provisions of this
            Agreement, the party to such action or proceeding which does not
            prevail will reimburse the prevailing party therein for the
            reasonable expenses of attorneys' fees and disbursements incurred by
            the prevailing party.

     12.12  Waiver. Waiver of performance of any obligation or term contained in
            this Agreement by any party, or waiver by one party of the other's
            default hereunder will not operate as a waiver of performance of any
            other obligation or term of this Agreement or a future waiver of the
            same obligation or a waiver of any future default.

Final Schedule    Schedule "A"
--------------
                                                          Page 16 of 17 Pages
<PAGE>

     IN WITNESS WHEREOF, Chesapeake and Gothic have executed this Agreement
as of the date first above written.

                                    GOTHIC ENERGY CORPORATION, an Oklahoma
                                    corporation

                                    By
                                      ------------------------------------
                                       Michael K. Paulk, President

                                    GOTHIC PRODUCTION COMPANY,
                                    an Oklahoma corporation

                                    By
                                      ------------------------------------
                                       Michael K. Paulk, President

                                    (jointly and severally referred to
                                     herein as "Gothic")

                                    CHESAPEAKE EXPLORATION LIMITED
                                    PARTNERSHIP, an Oklahoma
                                    limited partnership

                                    By:  Chesapeake Operating, Inc.,
                                         General Partner

                                    By
                                      ------------------------------------
                                       Aubrey K. McClendon,
                                       Chief Executive Officer

                                    ("Chesapeake")

Final Schedule    Schedule "A"
--------------
                                                           Page 17 of 17 Pages<PAGE>

                                                                    Exhibit 4.3

          INSTRUMENT OF RESIGNATION, APPOINTMENT AND ACCEPTANCE, dated as of
September 16, 1999,  among VENCOR OPERATING, INC., a Delaware corporation,
having its principal office at One Vencor Place, 680 South Fourth Street,
Louisville, Kentucky 40202 (the "Company"), VENCOR, INC., a Delaware
corporation, having its principal office at One Vencor Place, 680 South Fourth
Street, Louisville, Kentucky 40202 (the "Guarantor"), CHASE MANHATTAN TRUST
COMPANY, NATIONAL ASSOCIATION (successor to PNC Bank, National Association), a
national association duly organized and existing under the laws of the United
States, having its principal corporate trust office at One Oxford Centre, 301
Grant Street, Pittsburgh, PA 15219 (the "Resigning Trustee"), and HSBC BANK USA,
a banking corporation and trust company duly organized and existing under the
laws of the State of New York, having its principal corporate trust office at
140 Broadway, New York, New York 10005 (the "Successor Trustee");

                                   RECITALS
                                   --------

          There are presently issued and outstanding $300,000,000 in aggregate
principal amount of the Company's 9 7/8% Guaranteed Senior Subordinated Notes
due 2005 (the "Securities") under an Indenture, dated as of April 30, 1998 (the
"Indenture") between the Company, the Guarantor and the Resigning Trustee.

          The Resigning Trustee wishes to resign as Trustee, Registrar and
Paying Agent under the Indenture; the Company and the Guarantor wish to appoint
the Successor Trustee to succeed the Resigning Trustee as Trustee, Registrar and
Paying Agent under the Indenture; and the Successor Trustee wishes to accept
appointment as Trustee, Registrar and Paying Agent under the Indenture.

          NOW, THEREFORE, in consideration of the mutual covenants and promises
herein, the receipt and sufficiency of which is hereby acknowledged, the
Company, the Guarantor, the Resigning Trustee and the Successor Trustee agree as
follows:

                                  ARTICLE ONE
                             THE RESIGNING TRUSTEE

          Section 101.  Pursuant to Section 5.10 of the Indenture, the Resigning
          -----------
Trustee hereby notifies the Company and the Guarantor that the Resigning Trustee
is hereby resigning as Trustee under the Indenture.

          Section 102.  The Resigning Trustee hereby represents and warrants to
          -----------
the Successor Trustee that:

               (a)  No covenant or condition contained in the Indenture has been
          waived by the Resigning Trustee.
<PAGE>

               (b)  There is no action, suit or proceeding pending or, to the
          best of the knowledge of the responsible Trust Officers of the
          Resigning Trustee assigned to its Corporate Trust Department,
          threatened against the Resigning Trustee before any court or
          governmental authority arising out of any action or omission by the
          Resigning Trustee as Trustee under the Indenture.

          Section 103.  The Resigning Trustee hereby assigns, transfers,
          -----------
delivers and confirms to the Successor Trustee all right, title and interest of
the Resigning Trustee in and to the trust under the Indenture, and all the
rights, powers, trusts, privileges and duties of the Trustee under the
Indenture.  The Resigning Trustee shall execute and deliver such further
instruments and shall do such other things as the Successor Trustee may
reasonably require so as to more fully and certainly vest and confirm in the
Successor Trustee all the rights, powers, trusts, privileges and duties hereby
assigned, transferred, delivered and confirmed to the Successor Trustee.

          Section 104.  The Resigning Trustee hereby resigns as Paying Agent for
          -----------
the Securities, as Registrar for the Securities and as the office or agency
maintained by the Company and the Guarantor pursuant to Section 3.02 of the
Indenture.

          Section 105.  The Resigning Trustee agrees to indemnify the Successor
          -----------
Trustee and save the Successor Trustee harmless from and against any and all
costs, claims, liabilities, losses or damages whatsoever (including the
reasonable fees, expenses and disbursements of the Successor Trustee's counsel
and other advisors), that the Successor Trustee suffers or incurs without
negligence or bad faith on its part arising solely out of actions or omissions
of the Resigning Trustee.  The Successor Trustee will furnish to the Resigning
Trustee, promptly after receipt, all papers with respect to any action the
outcome of which would make operative the indemnity provided for in this
Section.  The Successor Trustee shall notify the Resigning Trustee promptly in
writing (and, in any event, within no later than the fifth Business Day) of any
claim for which it may seek indemnity.  The Resigning Trustee shall have the
option to defend the claim and the Successor Trustee shall cooperate fully in
the defense.  If the Resigning Trustee shall assume the defense, then the
Resigning Trustee shall not pay for separate counsel of the Successor Trustee.
The Resigning Trustee shall not be obligated to pay for any settlement made
without its consent.

                                  ARTICLE TWO
                         THE COMPANY and THE GUARANTOR

          Section 201.  (i)  The Company hereby certifies that annexed hereto
          -----------
marked Exhibit A is a copy of resolutions duly adopted by the Board of Directors
of the Company, and in full force and effect on the date hereof authorizing
certain officers of the Company to:  (a) accept the Resigning Trustee's
resignation as Trustee under the Indenture; (b) appoint the Successor Trustee as
Trustee under the Indenture; and (c) execute and deliver such agreements and
other instruments as may be necessary or desirable to effectuate the succession
of the Successor Trustee as Trustee under the Indenture.  The Company shall
deliver a Secretary's Certificate of the Secretary or an Assistant Secretary
certifying as to the annexed resolutions. (ii) The Guarantor hereby certifies
that annexed hereto marked Exhibit B is a copy of resolutions duly adopted by
the Board of Directors of the Guarantor, and in full force and effect on the
date

                                       2
<PAGE>

hereof authorizing certain officers of the Company to: (a) accept the Resigning
Trustee's resignation as Trustee under the Indenture; (b) appoint the Successor
Trustee as Trustee under the Indenture; and (c) execute and deliver such
agreements and other instruments as may be necessary or desirable to effectuate
the succession of the Successor Trustee as Trustee under the Indenture. The
Guarantor shall deliver a Secretary's Certificate of the Secretary or an
Assistant Secretary certifying as to the annexed resolutions.

          Section 202.  The Company and the Guarantor hereby appoint the
          -----------
Successor Trustee as Trustee under the Indenture and confirm to the Successor
Trustee all the rights, powers, trusts and duties of the Trustee under the
Indenture. The Company shall execute and deliver such further instruments and
shall do such other things as the Successor Trustee may reasonably require so as
to more fully and certainly vest and confirm in the Successor Trustee all the
rights, powers, privileges and duties hereby assigned, transferred, delivered
and confirmed to the Successor Trustee.

          Section 203.  The Company and the Guarantor hereby appoint the
          -----------
Successor Trustee as Paying Agent for the Securities, as Registrar for the
Securities and as the Company's and the Guarantor's office or agency maintained
pursuant to Section 3.02 of the Indenture.

          Section 204.  The Company hereby acknowledges and reaffirms its
          -----------
obligations to the Successor Trustee as set forth in Section 5.07 of the
Indenture, which obligations shall survive the execution hereof.

                                 ARTICLE THREE
                             THE SUCCESSOR TRUSTEE

          Section 301.  The Successor Trustee hereby represents and warrants to
          -----------
the Resigning Trustee, to the Company and to the Guarantor that the Successor
Trustee is qualified and eligible under the provisions of Section 5.09 of the
Indenture to act as Trustee under the Indenture.

          Section 302.  The Successor Trustee hereby accepts its appointment as
          -----------
Trustee under the Indenture and shall hereby be vested with all the rights,
powers, trusts and duties of the Trustee under the Indenture.

          Section 303. Promptly after the execution and delivery of this
          -----------
Instrument, the Successor Trustee shall cause a notice, a form of which is
annexed hereto marked Exhibit C, to be sent to each Holder of the Securities in
accordance with the provisions of the Indenture.

                                 ARTICLE FOUR
                                 MISCELLANEOUS

          Section 401.  Except as otherwise expressly provided or unless the
          -----------
context otherwise requires, all terms used herein which are defined in the
Indenture shall have the meanings assigned to them in the Indenture.

                                       3
<PAGE>

          Section 402.  This Instrument and the resignation, appointment and
          -----------
acceptance effected hereby shall be effective as of the close of business on the
date first above written upon the execution and delivery hereof by each of the
parties hereto.

          Section 403.  Notwithstanding the resignation of the Resigning Trustee
          -----------
effected hereby, the Company and the Guarantor shall remain obligated under
Section 5.07 of the Indenture to compensate, reimburse and indemnify the
Resigning Trustee in connection with its prior trusteeship under the Indenture.

          Section 404. This Instrument shall be governed by and construed in
          -----------
accordance with the laws of the jurisdiction which govern the Indenture and its
construction.

          Section 405.  This Instrument may be executed in any number of
          -----------
counterparts each of which shall be an original, but such counterparts shall
together constitute but one and the same instrument.

                  [Remainder of Page Intentionally Left Blank]

                                       4
<PAGE>

          IN WITNESS WHEREOF, the parties hereto have caused this Instrument of
Resignation, Appointment and Acceptance to be duly executed as of the day and
year first above written.
                                 VENCOR OPERATING, INC.

                                 By /s/ James H. Gillenwater, Jr.
                                    ------------------------------
                                    Name: James H. Gillenwater, Jr.
                                    Title: Senior Vice President

                                 VENCOR, INC.

                                 By /s/ James H. Gillenwater, Jr.
                                    ------------------------------
                                    Name: James H. Gillenwater, Jr.
                                    Title: Senior Vice President

                                 CHASE MANHATTAN TRUST COMPANY, NATIONAL
                                 ASSOCIATION

                                 By /s/ Francis J. Grippo
                                    ----------------------
                                    Name: Francis J. Grippo
                                    Title: Vice President

                                 HSBC BANK USA

                                 By /s/ Metin Caner
                                    ----------------
                                    Name: Metin Caner
                                    Title: Vice President
<PAGE>

                                   EXHIBIT A
                                   ---------

                               BOARD RESOLUTIONS
                                      of
                            VENCOR OPERATING, INC.
                            ----------------------

          The following is a true copy of resolutions duly adopted on
September 10, 1999, by the Board of Directors of Vencor Operating, Inc.:

          "RESOLVED, that any officer of this Company is hereby
          authorized to accept the resignation of The Chase Manhattan
          Bank (successor to PNC Bank, National Association), as
          Trustee under the Indenture, dated as of April 30, 1998, of
          Vencor Operating, Inc., and to appoint HSBC Bank USA as
          Successor Trustee under said Indenture; and

          FURTHER RESOLVED, that any officer of this Company is hereby
          authorized to enter into such agreements and other
          instruments as may be necessary or desirable to effectuate
          the appointment of said Successor Trustee under said
          Indenture."
<PAGE>

                                   EXHIBIT B
                                   ---------

                               BOARD RESOLUTIONS
                                      of
                                 VENCOR, INC.
                                 ------------

          The following is a true copy of resolutions duly adopted on
September 10, 1999, by the Board of Directors of Vencor, Inc.:

          "RESOLVED, that any officer of this Guarantor is hereby
          authorized to accept the resignation of The Chase Manhattan
          Bank (successor to PNC Bank, National Association), as
          Trustee under the Indenture, dated as of April 30, 1998, of
          Vencor Operating, Inc., and to appoint HSBC Bank USA as
          Successor Trustee under said Indenture; and

          FURTHER RESOLVED, that any officer of this Guarantor is
          hereby authorized to enter into such agreements and other
          instruments as may be necessary or desirable to effectuate
          the appointment of said Successor Trustee under said
          Indenture."
<PAGE>

                                   EXHIBIT C
                                   ---------

Notice to Holders of Vencor Operating, Inc. 9 7/8% Guaranteed Senior
Subordinated Notes due 2005:

          We hereby notify you of the resignation of The Chase Manhattan Bank
(successor to PNC Bank, National Association), as Trustee under the Indenture,
dated as of April 30, 1998, pursuant to which your Notes were issued and are
outstanding.

          Vencor Operating, Inc. and Vencor, Inc., as Guarantor of your Notes,
have appointed HSBC Bank USA, whose Corporate Trust Office is located at 140
Broadway, New York, New York 10005, as Successor Trustee under the Indenture,
which appointment has been accepted and has become effective.

                                    HSBC BANK USA,
                                    as Successor Trustee

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