Seller Collateral Debt Securities Purchase Agreement between American Capital Strategies, Ltd. and ACAS CRE CDO 2007-1 Depositor, LLC

"Closing Date": This term has the meaning set forth in Section 2(b).

"Collateral Debt Securities": This term has the meaning set forth in Section 2(a).

"Excluded Rights": With respect to an Collateral Debt Security, the right of the holder thereof to purchase any Underlying Term Loan as set forth in the related Underlying Instruments and any right to redeem or purchase other securities issued under such Underlying Instruments.

"Purchase Price": This term has the meaning set forth in Section 2(a).

"Repurchase Price": With respect to any Collateral Debt Security to be repurchased pursuant to Section 5, an amount equal to (i) the Purchase Price (as defined herein) of such Collateral Debt Security minus (ii) all principal paid to or on behalf of the Issuer prior to the date of such repurchase plus (iii) all accrued but unpaid interest thereon plus (iv) all unpaid costs and expenses (including, without limitation, costs and expenses incurred by third parties incurred in connection with such repurchase).

(a) Set forth in Annex A hereto is a list of obligations that shall be sold and contributed to the Depositor (the "Collateral Debt Securities") and certain other information with respect to each of the Collateral Debt Securities. The Seller agrees to sell and contribute to the Depositor, and the Depositor agrees to purchase from the Seller, each Collateral Debt Security listed in Annex A (other than any Excluded Rights, which Excluded Rights shall be retained by the Seller) at the purchase price in U.S. dollars identified for such Collateral Debt Security in Annex A (the "Purchase Price").

(b) Delivery or transfer of the Collateral Debt Securities shall be made on or about July 24, 2007 (the "Closing Date") at the time and in the manner agreed upon by the parties. Upon receipt of evidence of the delivery or transfer of the Collateral Debt Securities to the Depositor, the Depositor shall pay or cause to be paid to the Seller the Purchase Price in the manner agreed upon by the Seller and the Depositor.

(a) the representations and warranties contained herein shall be accurate and complete;

(b) the conditions to the closing under the Depositor Collateral Debt Securities Purchase Agreement shall have been satisfied or shall be satisfied simultaneously with the conditions contained herein;

(c) the conditions to the closing under that certain Purchase Agreement, dated as of the Closing Date, by and among the Issuer, the Co Issuer, Wachovia Capital Markets, LLC, Banc of America Securities LLC, J.P. Morgan Securities Inc., Deutsche Bank Securities Inc. and Merrill Lynch & Co. with respect to the Notes, shall have been satisfied or shall be satisfied simultaneously with the conditions contained herein;

(d) on the Closing Date, counsel for the Depositor shall have been furnished with all such documents, certificates and opinions as such counsel may reasonably request to evidence the accuracy and completeness of any of the representations, warranties or statements of the Seller, the performance of any of the obligations of the Seller hereunder or the fulfillment of any of the conditions herein contained; and

(e) the issuance of the Notes and receipt by the Depositor of the full payment required pursuant to the Depositor Collateral Debt Securities Purchase Agreement.

(a) Each party hereby represents and warrants to the other party that (i) it is duly organized or incorporated, as the case may be, and validly existing as an entity under the laws of the jurisdiction in which it is incorporated, chartered or organized, (ii) it has the requisite corporate power and authority to enter into and perform this Agreement, and (iii) this Agreement has been duly authorized by all necessary corporate action, has been duly executed by one or more duly authorized officers and is the valid and binding agreement of such party enforceable against such party in accordance with its terms.

(b) The Seller further represents and warrants to the Depositor that (i) on the Closing Date the Seller shall own the Collateral Debt Securities, shall have good and marketable title thereto, free and clear of any pledge, lien, security interest, charge, claim, equity or encumbrance of any kind, and upon the delivery or transfer of the Collateral Debt Securities to the Depositor as contemplated herein, the Depositor shall receive good and marketable title to the Collateral Debt Securities, free and clear of any pledge, lien, security interest, charge, claim, equity or encumbrance of any kind, (ii) the Seller acquired its ownership in the Collateral Debt Securities in good faith without notice of any adverse claim, and upon the delivery or transfer of the Collateral Debt Securities to the Depositor as contemplated herein, the Depositor shall acquire ownership in the Collateral Debt Securities in good faith without notice of any adverse claim, (iii) the Seller has not assigned, pledged or o therwise encumbered any interest in the Collateral Debt Securities (or, if any such interest has been assigned, pledged or otherwise encumbered, it has been released), (iv) the Underlying Instrument with respect to any Collateral Debt Security does not prohibit the Issuer from Granting a security interest in and assigning and pledging such Collateral Debt Security to the Trustee, (v) the information set forth with respect to the Collateral Debt Securities in Annex A hereto is correct, (vi) none of the execution, delivery or performance by the Seller of this Agreement shall (x) conflict with, result in any breach of or constitute a default (or an event that, with the giving of notice or passage of time, or both, would constitute a default) under, any term or provision of the organizational documents of the Seller, or any material indenture, agreement, order, decree or other material instrument to which the Seller is party or by which the Seller is bound that materially adversely affects the Seller's ability t o perform its obligations hereunder or (y) violate any provision of any law, rule or regulation applicable to the Seller of any regulatory body, administrative agency or other governmental instrumentality having jurisdiction over the Seller or its properties that has a material adverse effect, (vii) no consent, license, approval or authorization from, or registration or qualification with, any governmental body, agency or authority, nor any consent, approval, waiver or notification of any creditor or lessor (or any other person) is required in connection with the execution, delivery and performance by the Seller of this Agreement the failure of which to obtain would have a material adverse effect except such as have been obtained and are in full force and effect, (viii) the ownership of the Collateral Debt Securities will not cause the Issuer to be engaged in a trade or business within the United States, or have payments subject to foreign or United States withholding tax, (ix) with respect to any Collateral Debt Security that is a certificated security, such Collateral Debt Security is a certificated security in registered form, or is in uncertificated form held through the facilities of (a) The Depository Trust Company in New York, New York or (b) such other clearing organization or book-entry system as is designated in writing by the Issuer, (x) with respect to any Collateral Debt Security that is a certificated security, it has delivered to the Depositor or its designee such certificated security, along with any and all certificates, assignments and bond powers executed in blank, necessary to transfer such certificated security under the issuing documents of such Collateral Debt Security, (xi) to its knowledge, there is no monetary or material non-monetary event of default existing with regard to such Collateral Debt Security and (xii) based on the most recently available trustee report, (a) no interest shortfalls have occurred and no realized losses have been applied to any Collateral Debt Security and (b) it is not aware of any circumstances that could have a material adverse effect on such Collateral Debt Security.

(c) The Seller hereby acknowledges and consents to the assignment by the Depositor of this Agreement and all right, title and interest thereto to the Issuer and the collateral assignment by the Issuer to the Trustee, for the benefit of the Noteholders and the Interest Rate Swap Counterparty, as required in Sections 15.1(f)(i) and (ii) of the Indenture.

(d) The Seller hereby covenants and agrees that it shall perform any provisions of the Indenture made expressly applicable to the Seller by the Indenture as required by Section 15.1(f)(i) of the Indenture.

(e) The Seller hereby covenants and agrees that all of the representations, covenants and agreements made by or otherwise entered into by it in this Agreement shall also be for the benefit of the Trustee, the Noteholders and the Interest Rate Swap Counterparty as required by Section 15.1(f)(ii) of the Indenture.

(f) The Seller hereby covenants and agrees, as required by Section 15.1(f)(iv) of the Indenture, that it shall not enter into any agreement amending, modifying or terminating this Agreement (other than in respect of an amendment or modification of the type that may be made to the Indenture without Noteholder consent) or selecting or consenting to a successor manager, without notifying each Rating Agency and without the prior written consent and written confirmation of each Rating Agency that such amendment, modification or termination or selection of a successor manager, as applicable, will not cause the rating of the Notes to be reduced.

(a) Pursuant to Section 12.2 of the Indenture and Section 5 of the Depositor Collateral Debt Securities Purchase Agreement, upon discovery or receipt of written notice of a breach by the Seller of any representation, warranty or covenant under Section 4(b) that materially and adversely affects the value of any Collateral Debt Security, or of the interest therein of the Noteholders, the Depositor shall promptly notify the Seller in writing of such breach and request that the Seller cure such breach within 90 days from the date the Seller was notified of such breach, and if the Seller does not cure such breach in all material respects during such period, the Depositor shall cause the Seller to repurchase such Collateral Debt Security from the Depositor at the Repurchase Price on or prior to the next Payment Date following the expiration of such 90 day period. The Repurchase Price for the repurchased Collateral Debt Security shall be paid to the Depositor and the Depositor, upon receipt of w ritten certification from the Seller of such deposit, shall release to the Seller the related Collateral Debt Security and shall execute and deliver such instruments of transfer or assignment, in each case without recourse, as the Seller shall furnish to it and as shall be necessary to vest in the Seller any Collateral Debt Security released pursuant hereto and the Depositor shall have no further responsibility with regard to such Collateral Debt Security.

(b) Notwithstanding anything to the contrary contained herein, no recourse shall be had, whether by levy or execution or otherwise, for the payment of the principal of or interest or premium (if any) on the Collateral Debt Securities, or for any claim based on payments due thereon, against the Seller or any of its affiliates, stockholders, directors, officers, agents or employees under any rule of law, statute or constitution, or by the enforcement of any assessment or penalty, or otherwise, nor shall any defenses or judgment based thereon or with respect thereto; provided, however, it is understood and agreed that the obligation of the Seller to cure or to repurchase any Collateral Debt Security as to which a breach has occurred and is continuing shall constitute the sole remedy against the Seller respecting such breach available to the Depositor.

(a) THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK.

(b) The parties hereto hereby irrevocably submit to the jurisdiction of the United States District Court for the Southern District of New York and any court in the State of New York located in the City and County of New York, and any appellate court hearing appeals from the Courts mentioned above, in any action, suit or proceeding brought against it and to or in connection with this Agreement or the transaction contemplated hereunder or for recognition or enforcement of any judgment, and the parties hereto hereby irrevocably and unconditionally agree that all claims in respect of any such action or proceeding may be heard or determined in such New York State court or, to the extent permitted by law, in such federal court. The parties hereto agree that a final judgment in any such action, suit or proceeding shall be conclusive and may be enforced in other jurisdictions by suit on the judgment or in any other manner provided by law. To the extent permitted by applicable law, the parties her eto hereby waive and agree not to assert by way of motion, as a defense or otherwise in any such suit, action or proceeding, any claim that it is not personally subject to the jurisdiction of such courts, that the suit, action or proceeding is brought in any inconvenient forum, that the venue of the suit, action or proceeding is improper or that the subject matter thereof may not be litigated in or by such courts.

(c) To the extent permitted by applicable law, the parties hereto shall not seek and hereby waive the right to any review of the judgment of any such court by any court of any other nation or jurisdiction which may be called upon to grant an enforcement of such judgment.

(d) The Depositor irrevocably consents to the service of any and all process in any action or proceeding by the mailing or delivery of copies of such process to it at ACAS CRE CDO 2007-1 Depositor, LLC, c/o American Capital CRE Management, LLC, Two Bethesda Metro Center, 14th Floor, Bethesda, Maryland, 20814, Attention: Compliance Officer.

(e) The Seller irrevocably consents to the service of any and all process in any action or proceeding by the mailing or delivery of copies of such process to it at American Capital Strategies, Ltd., Two Bethesda Metro Center, 14th Floor, Bethesda, Maryland, 20814, Attention: Compliance Officer.