Exhibit 10.75**FIRST AMENDMENT TO****REAL ESTATE PURCHASE AND SALE AGREEMENT**     **THIS FIRST AMENDMENT TO REAL ESTATE PURCHASE AND SALE AGREEMENT**(this “Amendment”) isentered into as of February 16, 2007 by and among Rogers Street, LLC, a Delaware limited liabilitycompany and Lyme/Houston Development I, LP, a Delaware limited partnership and Kendall Square LLC,a Delaware limited liability company (collectively, the “Seller”) and BioMed Realty, L.P.,a Maryland limited partnership (the “Purchaser”), having an office at 17140 Bernardo CenterDrive, Suite 222, San Diego, California 92128, with a facsimile number of (858) 485-9843. TheSeller has an office c/o Lyme Properties LLC, 101 Main Street, 18th floor, Cambridge, MA02142 Attn: Robert L. Green, with a facsimile number of (617) 225-2133. Any written consent orapproval given by Kendall Square LLC shall be deemed to have been given by Seller.     The parties desire to make certain amendments to a certain Real Estate Purchase and SaleAgreement entered into by them with an Effective Date of January 29, 2007 (the “P&S”).     Capitalized terms used but not otherwise defined herein shall have the meanings given suchterms in the P&S.     In consideration of the mutual promises hereinafter set forth and for other good and valuableconsideration, the receipt and sufficiency of which are hereby acknowledged, the undersigned agreeas follows:     1. **Section 1.1****.**Section 1.1 of the P&S is hereby amended by:          (a) Deleting the definition of “Environmental Insurance Policies” in its entirety andreplacing it with the following:          ““Environmental Insurance Policies” shall mean (i) the environmental insurancepolicies listed on the attached Schedule 7.2(a) and (ii) Zurich Steadfast Insurance Co.Environmental Response, Compensation & Liability Insurance Policy No. PLC3677154-00.”          (b) Inserting the following definition immediately after the definition of “MicrobiaDocuments”:          ““Microbia Letter of Credit” shall mean that certain irrevocable standby letter ofcredit, No. SVB02IS4087, dated January 10, 2002, issued by Silicon Valley National Bank in favor ofRogers Street LLC, as beneficiary, as amended and extended.”
 

 
          (c) Deleting the definition of “Parcel E East Development Rights” in its entirety andreplacing it with the following:          ““Parcel E East Development Rights” shall mean the right to develop approximately87,000 square feet (as defined in applicable Cambridge zoning ordinances) of space in accordancewith the Notice of Right of First Offer on so-called Parcel E East (as such term is defined in theSpecial Permit).”          (d) Deleting the definition of Principal Guaranty in its entirety and replacing it with thefollowing:          ““Principal Guaranties” shall mean (i) that Guaranty of Payment, dated November 5,2003, given by Principal Life Insurance Company to Kendall Square LLC and related to a certain SiteWork Payment and (ii) that Guaranty of Completion, dated November 5, 2003, given by Principal LifeInsurance Company to Kendall Square LLC and related to Parcel E-1H.”          The P&S is hereby further amended by replacing the term “Principal Guaranty” wherever it occurs inthe P&S with the term “Principal Guaranties”.          (e) Deleting the definition of “Title Company” in its entirety and replacing it with thefollowing:          ““Title Company” shall mean the Boston, Massachusetts office of Stewart Title GuarantyCompany, having an address of 99 Summer Street, 2nd Floor, Boston, Massachusetts 02110, Attention:Marie Franco, Esq.; except that, only with respect to the Title Commitment that has been provided,and the Title Policy that will be provided, for the Houston Real Property, “Title Company” shallmean Commonwealth Land Title Insurance Company.”     2. **Section 2.2(a)****.**Section 2.2(a) of the P&S is hereby deleted in its entirety andreplaced with the following:          The purchase price for the Property shall be the sum of Four Hundred Eighty Nine MillionDollars ($489,000,000), plus or minus the Reconciliation Amount described below (the “PurchasePrice”). Subject to the adjustments and apportionments set forth in this Agreement, thePurchase Price shall be paid on the Closing Date by wire transfer of immediately available federalfunds to such account(s) of Seller as Seller designates in writing to Purchaser. Seller andPurchaser agree that the Purchase Price shall be allocated as follows:     (1) Rogers Street Real Property: $348,000,000(2) Houston Real Property $9,000,000 and(3) Kendall Square Real Property $132,000,000.          With respect to the allocation of the Purchase Price to the Kendall Square Real Property, thesum of Twelve Million Three Hundred Fifty Thousand Dollars ($12,350,000) has been allocated to theParcel E East Development Rights and the sum of Six Million Dollars
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($6,000,000) has been allocated to Parcel E-1H. The foregoing allocation is not intended andshall not be construed to allow Seller to sell or Purchaser to buy less than all of the Property.          3. **Section 6.1****.**Section 6.1 of the P&S is hereby amended by:          (a) Deleting the first two sentences of Section 6.1(c) in their entirety and replacing themwith the following:          “Purchaser shall have received estoppel certificates (each, a “Tenant EstoppelCertificate”) from the following Tenants of the Rogers Street Real Property: Schering PloughResearch Institute, as tenant at 320 Bent Street, Microbia, Inc., as tenant at 320 Bent Street, andMicrobia, Inc., as tenant at 301 Binney Street, or shall have been provided with a Seller’sEstoppel Certificate as permitted by the following sentence, in each case dated no earlier than theEffective Date (the “Estoppel Requirement”). If Rogers Street, LLC is unable to obtain anestoppel certificate from Microbia, Inc., as tenant at 320 Bent Street or 301 Binney Street, inorder to meet the Estoppel Requirement, Rogers Street, LLC shall provide to the Purchaser aSeller’s Estoppel Certificate with respect to either such Lease.”          (b) Adding the following provisions to Section 6.1 as clauses (s), (t) and (u) thereof,respectively:          “(s) Seller shall deliver to Purchaser, with respect to Kendall Square Corporation: (i) aresignation of the incumbent directors of the corporation appointed by Seller with respect to itsinterests in the Kendall Square Real Property, (ii) an appointment by Seller, as a member of thecorporation, as directors with respect to the interests in the Kendall Square Real Property thoseindividuals designated by Purchaser, (iii) a resignation of the existing officers of thecorporation, (iv) a certificate of the secretary of the corporation with complete copies of thecurrent articles of incorporation and bylaws of the corporation, and (v) a certificate of goodstanding issued by the Secretary of the Commonwealth of Massachusetts with respect to thecorporation.          (t) Seller shall have caused the words “Rogers Street LLC” in paragraphs 2(A) and 2(B) of theMicrobia Letter of Credit to be replaced by the word “Beneficiary”.          (u) If (i) any condition to closing favoring either Purchaser or Seller is not satisfied onthe Closing Date (as the same may be adjourned or extended under any express right herein), (ii)such party does not waive such condition and (iii) the failure of such condition does not resultfrom the breach of this Agreement by such party, then such party may terminate this Agreement bydelivery of written notice to the other party. Upon any such termination, without further actionof the parties, this Agreement shall become null and void and no party shall have any furtherrights or obligations under this Agreement, except the return of the Deposit to the Purchaser andthe Surviving Obligations.”     4. **Section 7.2(b)****.**Section 7.2(b) of the P&S is hereby amended by adding thefollowing provision to Section 7.2(b) as clause (xi) thereof:
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          (xi) As of the Closing Date, no more than Twenty Five Thousand Dollars ($25,000) shall remainto be paid by Kendall Square LLC under that certain construction contract dated as of March 8, 2006between Kendall Square LLC and James W. Flett Co., Inc.     5. **Section 8.2(j)****.**Section 8.2(j) of the P&S is hereby amended by inserting thewords “including the Microbia Letter of Credit,” immediately following the third comma in suchsection.     6. **Schedule 6.****1(h)****-2****.**The P&S is hereby amended by deleting Schedule 6.1(h)-2 in itsentirety and replacing it with Exhibit A attached hereto.     7. **Schedule 6.****1(h)****-3****.**The P&S is hereby amended by deleting Schedule 6.1(h)-3 in itsentirety and replacing it with Exhibit B attached hereto.     8. **Schedule 6.1(j)****.**The P&S is hereby amended by deleting Schedule 6.1(j) in itsentirety and replacing it with Exhibit C attached hereto.     9. **Schedule 6.6****.**The P&S is hereby amended by deleting Schedule 6.6 in its entiretyand replacing it with Exhibit D attached hereto.     10. **Schedule 7.2(a)****.**The P&S is hereby amended by deleting Schedule 7.2(a) in itsentirety and replacing it with Exhibit E attached hereto.     11. **Schedule 7.****2(b)(iv)****-6****.**The P&S is hereby amended by adding the permits listed onExhibit F attached hereto to the list of Permits for the Kendall Square Real Propertylisted Schedule 7.2(b)(iv)-(6) attached to the P&S.     12. **Schedule 8.****2(a)****-1****.**The P&S is hereby amended by deleting Schedule 8.2(a)-1 inits entirety and replacing it with Exhibit G attached hereto.     13. **Schedule 8.****2(a)****-2****.**The P&S is hereby amended by deleting Schedule 8.2(a)-2 inits entirety and replacing it with Exhibit H attached hereto.     14. **Schedule 8.2(b)****.**The P&S is hereby amended by deleting Schedule 8.2(b) in itsentirety and replacing it with Exhibit I attached hereto.     15. **Schedule 8.2(e)****.**The P&S is hereby amended by deleting Schedule 8.2(e) in itsentirety and replacing it with Exhibit J attached hereto.     16. **Constellation****.**Seller shall use reasonable efforts, and Purchaser shallcooperate and assist in such efforts, to obtain from Constellation Charitable Foundation a certain$1,000,000 “Grantee Letter of Credit” referred to in Section 1.6.2 of Exhibit B to that certaindeed from Kendall Square LLC to Constellation Charitable Foundation dated as of September 27, 2002and recorded in Middlesex South District Registry of Deeds in Book 36539, Page 513. In no event
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shall the obtaining of such Grantee Letter of Credit be a condition of Closing under the P&S,as the same has been amended hereby.     17. **Phase III Draft****.**Reference is made to that certain “DRAFT Addendum to PhaseIII-Identification, Evaluation and Selection of Comprehensive Remedial Action Alternatives,Off-Property Area, 364 Third Street, Cambridge, Massachusetts, RTN 3-4570 dated February 2007”included among the Reports in Schedule 7.2(b)(iv)-5 to the P&S (“Phase III Draft”).Until the Closing Seller will cooperate with and assist Purchaser in pursuing applicableregulatory approvals with respect to the matters referred to in the Phase III Draft and willcooperate with and assist Purchaser with making appropriate claims under applicable environmentalinsurance policies. Such cooperation and assistance will include, without limitation, filing thePhase III Draft with applicable regulatory authorities in such form as Purchaser authorizes inwriting, conducting applicable public meetings and reviews with respect thereto, filing claimsunder applicable environmental insurance policies in such form as Purchaser authorizes in writing,and making recommendations to Purchaser with respect to all of the foregoing. No such filingsshall be Updates under this Agreement. Neither the obtaining of any regulatory approvals nor therecognition of any environmental claims under environmental insurance policies shall be conditionsto Closing under the P&S.     18. **Study Period/Section 4.1**. Upon the execution of this Amendment by Purchaser, theStudy Period shall be deemed expired, Purchaser shall be deemed to have waived any right to give aTitle Objection Notice or to make any Purchaser Title Objections under Section 4.1 of the P&S, andthe P&S (including, without limitation, the Updates distributed to Purchaser on February 13, 2007),as amended hereby, shall be ratified and confirmed.[Remainder of Page Left Intentionally Blank]
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     **IN WITNESS WHEREOF**, Seller and Purchaser hereto have executed this Amendment as of the datefirst written above.     **SELLER**:     ROGERS STREET, LLC, a Delaware limited liability company     By: The Lyme Timber Company, a New Hampshire limited partnership, its sole