TMFI MORTGAGE LOAN PURCHASE AGREEMENT

EXECUTION

THIS TMFI MORTGAGE LOAN PURCHASE AGREEMENT, dated as of February 1, 2007 (the “ Agreement ”), is made and entered into between Thornburg Mortgage Home Loans, Inc., a Delaware corporation (the “ Seller ”) and Thornburg Mortgage Funding, Inc., a Delaware corporation (the “ Purchaser ”).

WHEREAS, the Seller is the owner of the notes or other evidence of indebtedness (the “ Mortgage Notes ”) so indicated on Schedule I hereto referred to below, and the other documents or instruments constituting the Mortgage File (collectively, the “ Mortgage Loans ”); and

WHEREAS, the Seller, as of the date hereof, owns the mortgages or deeds of trust (the “ Mortgages ”) on the properties (the “ Mortgaged Properties ”) securing such Mortgage Loans, including rights to (a) any property acquired by foreclosure or deed in lieu of foreclosure or otherwise, (b) the proceeds of any insurance policies covering the Mortgage Loans or the Mortgaged Properties or the obligors on the Mortgage Loans and (c) the Seller’s security interest in any Additional Collateral; and

WHEREAS, the Seller is a party to the servicing agreements identified on Schedule II (each a “ Servicing Agreement ,” and together the “ Servicing Agreements ”), and certain of the Mortgage Loans are currently being serviced thereunder by the servicers identified therein; and

WHEREAS, the parties hereto desire that the Seller sell the Mortgage Loans, the Mortgages and the related assets referred to above, and assign the Seller’s rights under the Servicing Agreements to the Purchaser, other than any servicing rights retained pursuant to the provisions of the Servicing Agreements, but only to the extent such rights relate to the servicing of the Mortgage Loans (the “ Contractual Rights ”) pursuant to the terms of this Agreement with the understanding that Purchaser on the Closing Date will in turn assign such Mortgage Loans, the Mortgages and the related assets and the Contractual Rights to Structured Asset Securities Corporation, a Delaware corporation (“SASCO”) pursuant to the terms of the SASCO mortgage loan purchase agreement dated as of February 1, 2007 between the Purchaser and SASCO (the “SASCO MLPA”); and

WHEREAS, pursuant to the terms of that certain Sale and Servicing Agreement dated as of February 1, 2007 (the “ Sale and Servicing Agreement ”) among Thornburg Mortgage Securities Trust 2007-1 (the “ Trust ”), as issuer (the “ Issuer ”), SASCO, as depositor (the “ Depositor ”), the Seller, as initial seller, the Purchaser, as seller, Wells Fargo Bank, N.A., as master servicer and securities administrator and LaSalle Bank National Association, as indenture trustee (the “ Indenture   Trustee ”), SASCO will convey the Mortgage Loans, the Mortgages and the related assets, the Contractual Rights and rights provided to the Purchaser hereunder on the Closing Date to the Issuer; and

WHEREAS on the Closing Date, the Issuer will pledge the Mortgage Loans, the Mortgages and related assets, the Contractual Rights and certain rights provided to the Purchaser hereunder to the Indenture Trustee under an Indenture dated as of February 1, 2007 (the “ Indenture ”) between the Issuer and the Indenture Trustee, pursuant to which the Issuer shall issue its Mortgage-Backed Notes, Series 2007-1 (the “ Notes ”), the payment of which is to be secured by such pledged assets.

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

Section 1.01.   Definitions .   Any capitalized term used but not defined herein shall have the meaning assigned thereto in the Sale and Servicing Agreement and the Indenture.

Section 2.01.   Sale of Mortgage Loans; Assignment of the Contractual Rights .   The Seller, concurrently with the execution and delivery of this Agreement, does hereby sell, assign, set over, and otherwise convey to the Purchaser, without recourse, all of its right, title and interest in, to and under (i) each Mortgage Loan, including the related Cut-Off Date Principal Balance, and all collections in respect of interest and principal due after the Cut-Off Date (and all principal received before the Cut-Off Date to the extent such principal relates to a Monthly Payment due after the Cut-Off Date); (ii) property which secured such Mortgage Loan and which has been acquired by foreclosure or deed in lieu of foreclosure; (iii) its interest in any insurance policies in respect of the Mortgage Loans; (iv) any Additional Collateral with respect to the Mortgage Loans; and (v) all proceeds of any of the foregoing.

Concurrently with the execution and delivery of this Agreement, the Seller hereby assigns to the Purchaser the Contractual Rights. The Purchaser hereby accepts such assignment, and shall be entitled to exercise such Contractual Rights under each Servicing Agreement as if the Purchaser had been a party to each such agreement.

Section 2.02.   Obligations of the Seller Upon Sale and Assignment .   In connection with the transfer and assignment pursuant to Section 2.01 hereof, the Seller further agrees, at its own expense, on or prior to the Closing Date, (a) to indicate in its books and records that the Mortgage Loans have been sold to the Purchaser pursuant to this Agreement and (b) to deliver to the Purchaser a computer file containing a true and complete list of all such Mortgage Loans specifying for each such Mortgage Loan, as of the Cut-Off Date, (i) its account number and (ii) the Cut-Off Date Principal Balance and such file, which forms a part of Schedule A to the Sale and Servicing Agreement, shall also be marked as Schedule I to this Agreement and is hereby incorporated into and made a part of this Agreement.

The Seller hereby confirms to the Purchaser that it has made the appropriate entries in its general accounting records, to indicate that the Mortgage Loans have been transferred as directed by the Purchaser.

The Purchaser hereby acknowledges its acceptance of all rights, title and interests in, to and under the Mortgage Loans and other property, and the Contractual Rights, now existing or hereafter created, conveyed to it pursuant to Section 2.01 hereof.

The parties hereto intend that the transaction set forth herein be a non-recourse sale by the Seller to the Purchaser of all of the Seller’s rights, title and interests in, to and under the Mortgage Loans and other property described in Section 2.01. Nonetheless, in the event the transaction set forth herein is deemed not to be a sale, the Seller hereby grants to the Purchaser a security interest in all of the Seller’s rights, title and interests in, to and under the Mortgage Loans and other property described in Section 2.01, whether now existing or hereafter created, to secure all of the Seller’s obligations hereunder; and this Agreement shall constitute a security agreement under applicable law. The Seller and the Purchaser shall, to the extent consistent with this Agreement, take such actions as may be necessary to ensure that, if this Agreement were deemed to create a security interest in the Mortgage Loans and the Contractual Rights, such security interest would be deemed to be a perfected security interest of first priority under applicable law and will be maintained as such throughout the term of the Indenture.

Section 2.03.   Payment of Purchase Price for the Mortgage Loans .   In consideration of the sale of the Mortgage Loans, the related assets and the Contractual Rights from the Seller to the Purchaser on the Closing Date, the Purchaser agrees to pay to the Seller on the Closing Date by transfer of immediately available funds, an amount equal to $1,475,654,383.67 (which amount includes accrued interest) (the “ Purchase Price ”) minus any expenses billed to the Purchaser in connection with the issuance and offering of the Notes pursuant to the SASCO Mortgage Loan Purchase Agreement.

Section 3.01.   Seller Representations and Warranties Relating to the Mortgage Loans .   The Seller hereby makes the representations and warranties set forth in Schedule III hereto applicable to the Mortgage Loans and by this reference incorporated herein, to the Purchaser, as of the Closing Date or, if applicable, such other date as may be specified therein, with the understanding that the Purchaser pursuant to the terms of the SASCO Mortgage Loan Purchase Agreement will assign to the Depositor, which will assign to the Issuer, which will assign to the Indenture Trustee any and all rights and remedies the respective party may have against the Seller arising from a breach of any such representation and warranty.

Section 3.02.     Seller’s Representations and Warranties .   The Seller represents, warrants and covenants to the Purchaser as of the Closing Date or as of such other date specifically provided herein:

(i)   the Seller is duly organized, validly existing and in good standing as a corporation under the laws of the State of Delaware and is and will remain in compliance with the laws of each state in which any Mortgaged Property is located to the extent necessary to fulfill its obligations hereunder;

(ii)   the Seller has the power and authority to hold each Mortgage Loan, to sell each Mortgage Loan, to execute, deliver and perform, and to enter into and consummate, all transactions contemplated by this Agreement. The Seller has duly authorized the execution, delivery and performance of this Agreement, has duly executed and delivered this Agreement and this Agreement, assuming due authorization, execution and delivery by the Purchaser, constitutes a legal, valid and binding obligation of the Seller, enforceable against it in accordance with its terms except as the enforceability thereof may be limited by bankruptcy, insolvency or reorganization or other similar laws in relation to the rights of creditors generally;

(iii)   the execution and delivery of this Agreement by the Seller and the performance of and compliance with the terms of this Agreement will not violate the Seller’s certificate of incorporation or by-laws or constitute a material default under or result in a material breach or acceleration of, any material contract, agreement or other instrument to which the Seller is a party or which may be applicable to the Seller or its assets;

(iv)   the Seller is not in violation of, and the execution and delivery of this Agreement by the Seller and its performance and compliance with the terms of this Agreement will not constitute a violation with respect to, any order or decree of any court or any order or regulation of any federal, state, municipal or governmental agency having jurisdiction over the Seller or its assets, which violation might have consequences that would materially and adversely affect the condition (financial or otherwise) or the operation of the Seller or its assets or might have consequences that would materially and adversely affect the performance of its obligations and duties hereunder;

(v)   the Seller does not believe, nor does it have any reason or cause to believe, that it cannot perform each and every covenant contained in this Agreement;

(vi)   the Seller has good, marketable and indefeasible title to the Mortgage Loans, free and clear of any and all liens, pledges, charges or security interests of any nature encumbering the Mortgage Loans;

(vii)   the Mortgage Loans are not being transferred by the Seller with any intent to hinder, delay or defraud any creditors of the Seller;

(viii)   there are no actions or proceedings against, or investigations known to it of, the Seller before any court, administrative or other tribunal (A) that might prohibit its entering into this Agreement, (B) seeking to prevent the sale of the Mortgage Loans or the consummation of the transactions contemplated by this Agreement or (C) that might prohibit or materially and adversely affect the performance by the Seller of its obligations under, or validity or enforceability of, this Agreement;

(ix)   no consent, approval, authorization or order of any court or governmental agency or body is required for the execution, delivery and performance by the Seller of, or compliance by the Seller with, this Agreement or the consummation of the transactions contemplated by this Agreement, except for such consents, approvals, authorizations or orders, if any, that have been obtained; and

(x)   the consummation of the transactions contemplated by this Agreement are in the ordinary course of business of the Seller, and the transfer, assignment and conveyance of the Mortgage Notes and the Mortgages by the Seller pursuant to this Agreement are not subject to the bulk transfer or any similar statutory provisions.

Section 3.03.   Remedies for Breach of Representations and Warranties .   It is understood and agreed that (i) the representations and warranties set forth in Sections 3.01 and 3.02 and the provisions of Article V, shall survive the purchase of the Mortgage Loans and the Contractual Rights hereunder (and in the case of Section 3.01, shall survive delivery of the respective Mortgage Files to the Indenture Trustee pursuant to the SASCO Mortgage Loan Purchase Agreement and the Sale and Servicing Agreement) and shall inure to the benefit of the Purchaser and its assigns notwithstanding any restrictive or qualified endorsement on any Mortgage Note or Assignment or the examination or lack of examination of any Mortgage File and (ii) the remedies for the breach of such representations and warranties and for the failure to deliver the documents referred to in Section 2.02 hereof shall be as set forth in Section 2.04 of the Sale and Servicing Agreement.

Section 4.01.   Covenants of the Seller .   The Seller hereby covenants that, except for the transfer hereunder, it will not sell, pledge, assign or transfer to any other Person, or grant, create, incur, assume or suffer to exist any Lien on any Mortgage Loan, or any interest therein; it will notify the Purchaser, of the existence of any Lien on any Mortgage Loan immediately upon discovery thereof; and it will defend the right, title and interest of the Purchaser and its assigns, in, to and under the Mortgage Loans, against all claims of third parties claiming through or under the Seller; provided , however , that nothing in this Section 4.01 shall prevent or be deemed to prohibit the Seller from suffering to exist upon any of the Mortgage Loans any Liens for municipal or other local taxes and other governmental charges if such taxes or governmental charges shall not at the time be due and payable or if the Seller shall currently be contesting the validity thereof in good faith by appropriate proceedings and shall have set aside on its books adequate reserves with respect thereto.

Section 5.01.   Indemnification .   The Seller agrees to indemnify and to hold each of the Purchaser, the Depositor, the Issuer, the Indenture Trustee, each of the officers and directors of each such entity and each person or entity who controls each such entity or person harmless against any and all claims, losses, penalties, fines, forfeitures, legal fees and related costs, judgments, and any other costs, fees and expenses that the Purchaser, the Depositor, the Issuer, the Indenture Trustee, or any such person or entity may sustain in any way related to the failure of the Seller to perform its duties in compliance with the terms of this Agreement. The Seller shall immediately notify the Purchaser, the Depositor, the Issuer and the Indenture Trustee if a claim is made under this provision. The Seller shall assume the defense of any such claim and pay all expenses in connection therewith, including reasonable counsel fees, and promptly pay, discharge and satisfy any judgment or decree which may be entered against the Purchaser, the Depositor, the Issuer, the Indenture Trustee or any such person or entity in respect of such claim.

Section 6.01.   Termination .   The respective obligations and responsibilities of the Seller and the Purchaser created hereby shall terminate, except for the respective indemnity obligations as provided herein, upon the termination of the Sale and Servicing Agreement as provided in Article X thereof.

Section 7.01.   Amendment .   This Agreement may be amended from time to time by the Seller and the Purchaser by written agreement signed by the parties hereto.

Section 7.02.   Governing Law .   This Agreement shall be governed by and construed in accordance with the laws of the State of New York, without reference to its conflict of law provisions (other than Section 5-1401 of the General Obligations Law), and the obligations, rights and remedies of the parties hereunder shall be determined in accordance with such laws.

Section 7.03.   Notices .   All demands, notices and communications hereunder shall be in writing and shall be deemed to have been duly given if personally delivered at or mailed by registered mail, postage prepaid, addressed as follows:

if to the Seller:

Thornburg Mortgage Home Loans, Inc.

150 Washington Avenue, Suite 302

Santa Fe, New Mexico 87501

Attention: Deborah Burns

or such oth