**Exhibit 10.6****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 November 2, 2006 by and between CLSB I, LLC, a Delaware limited liabilitycompany (the “Seller”), having an office c/o Lyme Properties LLC, 101 Main Street,18th floor, Cambridge, MA 02142 Attn: Robert L. Green and BioMed Realty, L.P., aMaryland limited partnership (the “Purchaser”), having an office at 17140 Bernardo CenterDrive, Suite 222, San Diego, California 92128. CLSB II, LLC, a Delaware limited liability company(the “CLSB II Assignor”) having an office c/o Lyme Properties, LLC, 101 Main Street,18th floor, Cambridge, MA 02142 Attn: Robert L. Green, has also executed this Agreementfor the purposes of provisions applicable to it, if any.      The parties desire to make certain amendments to a certain Purchase and Sale Agreement enteredinto by them with an Effective Date of October 20, 2006 (“P&S”).      Capitalized terms used herein and not otherwise defined shall have the meaning given in theP&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 parties heretoagree that the P&S will be amended as follows:1. In the first sentence of Section 6.4(a) before the first proviso, each use of theword “Lease” shall be replaced with the word “lease”. 2. In the first sentence of Section 6.4(b) before the first proviso, the words “or othercontracts” shall be added after the word “Other Matters” in each instance. 3. Each of the items listed in clause 8.2(j)(ii) shall be delivered to Purchaser at theClosing (or to any lender that Purchaser designates in writing to Seller at least five (5)business days prior to Closing). In addition, at the Closing Seller shall deliver toPurchaser each document or instrument that is reasonably required to transfer any such itemsto Purchaser or such lender. 4. The first two sentences of Section 11.3 shall be amended and restated in theirentirety as follows:   “Neither this Agreement nor any interest hereunder shall be assigned ortransferred by Seller or Purchaser; provided, however, that Purchaser mayassign its rights hereunder at Closing to any Permitted Assignee,and
 

 
    Purchaser may designate any single purpose entity or entities that arewholly owned and controlled by Purchaser or by Purchaser’s REIT Entity totake title to the Property and to execute and deliver the documents to beexecuted and delivered by Purchaser hereunder in connection with the Closing(any such entity, a “Permitted Assignee” hereunder). For purposes ofclarity, Purchaser shall have the right to assign its right to take title toall or any portion of the Property under this Agreement to one or moreseparate single-purpose entities that are wholly owned and controlled byPurchaser or Purchaser’s REIT Entity solely for the purposes of such entitytaking title at Closing and executing such documents, but the Purchasernamed herein (i.e., BioMed Realty, L.P.) shall not be released hereunder andshall continue to be liable for all the covenants and obligations of“Purchaser” hereunder and shall execute and deliver at Closing any requiredinstruments and documents that “Purchaser” (as opposed to suchsingle-purpose entities) may be required to deliver hereunder.”5. The parties have agreed that the CLSB II Purchase Money Loan will not be sold or purchased.Consequently, all references in the P&S to “CLSB II Purchase Money Loan” and “CLSB IIAssignor” and all provisions relating to such Loan and CLSB II Assignor (including withoutlimitation Section 2.2(c)(5)) are hereby deemed deleted and the Purchase Price ishereby reduced by Seventeen Million Six Hundred Thousand Dollars ($17,600,000) and is nowagreed to be Four Hundred Eighty-Nine Million, Seven Hundred Seventy Thousand Dollars($489,770,000). 6. In addition to the Seller’s and Purchaser’s deliveries set forth in Sections 8.2 and8.3, Seller and Purchaser shall execute and deliver at the Closing an Assignment andAssumption Agreement in the form of Schedule BRA Assignment and Assumption Agreementattached hereto. 7. In addition to the Seller’s deliveries set forth in Section 8.2, Seller shall delivera certificate of BIDMC substantially in the form attached as Schedule BIDMC ROFOCertificate or in such other form as shall reasonably meet the standards set forth for thecertificate required to be delivered by BIDMC under the Quitclaim Deed (Blackfan ResearchCenter Parcel) from BIDMC to Seller dated June 24, 2005 and recorded with Suffolk CountyRegistry of Deeds in Book 37389, Page 151, reciting compliance with certain purchase rights asset forth in such Deed. 8. On Monday, November 6, 2006, Seller will send the easement estoppels substantially in theform attached as Schedule Easement Estoppels (“Easement Estoppels”) to BIDMCand to Longwood Research Institute, Inc. requesting such estoppels with respect to thatcertain Cross Easement Agreement recorded with Suffolk County Registry of Deeds in Book 37389,Page 173, and that certain Mutual Garage Easement, Exclusive Use Easements, Support RightsEasement Agreement and Notice of Garage Regulation and Operating Agreement recorded with saidDeeds in Book 37390, Page 1. If one or more such Easement Estoppels is not obtained by theClosing, at its election Seller may give a Seller’s Estoppel Certificate with respect theretoor may adjourn the Closing for up to
 

 
  sixty (60) days in order to obtain such Easement Estoppel. If Seller elects to give aSeller’s Estoppel Certificate, such Seller’s Estoppel Certificate shall be substantially inthe form of the Schedule Easement Estoppels but shall also contain the followingprovisions: “This Estoppel is delivered by Seller to Purchaser pursuant to a Real EstatePurchase and Sale Agreement between Seller and Purchaser dated ___, ___, 200___(the“Purchase Agreement”) which provides for a Seller Estoppel Certificate, and Seller’sliability hereunder shall be subject to all time, dollar and other limitations on Seller’sliability set forth in the Purchase Agreement and to the other provisions of the PurchaseAgreement that apply to a Seller Estoppel Certificate. Whenever a representation herein isqualified by the phrase “to Seller’s knowledge”, or by words of similar import, suchknowledge shall be limited as provided in the Purchase Agreement. No officer, director,owner, manager, trustee, or agent of Seller shall have any liability hereunder. As usedherein, knowledge means the actual knowledge possessed by Seller as of the date hereofwithout having any duty to make, or having made, any inquiry.” Receipt of EasementEstoppels, either from such other parties or from Seller, shall be a condition of Closingfor the benefit of Purchaser in addition to the Seller’s deliveries set forth in Section 8.2of the P&S. Seller shall be entitled to continue to deal with BIDMC and Longwood ResearchInstitute, Inc. after Closing to attempt to obtain an Easement Estoppel. If Purchasersubsequently receives an Easement Estoppel from either BIDMC or Longwood Research Institute,Inc. for whom Seller has delivered a Seller’s Estoppel Certificate, Seller shall thereuponbe released from liability with respect to the Seller’s Estoppel Certificate given withrespect to such Person to the extent that the information contained in the Easement Estoppelso obtained is materially consistent with the information contained in Seller’s EstoppelCertificate. In addition to the foregoing, receipt of the Turnkey Garage Estoppel, eitherfrom BIDMC or from Seller (in the form of a Seller’s Estoppel Certificate incorporating theforegoing provisions and otherwise in the same manner and subject to the same rights andobligations as is the case with Seller’s Estoppel Certificates given with respect toEasement Estoppels), shall be a condition of Closing for the benefit of Purchaser inaddition to the Seller’s deliveries set forth in Section 8.2 of the P&S. No EasementEstoppels (or Seller’s Estoppel Certificate delivered on account thereof) shall counttowards the requirement to deliver Easement Estoppels hereunder if the same (A) disclosesany material default by Seller or another party to any agreement that is the subject of suchEasement Estoppel or (B) contains information that is materially inconsistent with theinformation set forth in such agreements as made available to Purchaser before thecommencement of the Restricted Period or (C) discloses any information that would make anySeller Representation untrue in any material respect. 9. On Monday, November 6, 2006, Seller will send the TAPA amendment form substantially in theform attached hereto as Schedule TAPA Amendment requesting that the BostonTransportation Department state that it will approve an executed copy of such form. Inaddition to the Seller’s deliveries set forth in Sections 8.2, at the Closing Seller willexecute and deliver the form of Schedule TAPA Amendment; but such statement by theBoston Transportation Department is not a condition of Closing. 10. Schedule 2.2 as attached to the P&S is deleted and Schedule 2.2 Revised as attachedhereto is substituted in place thereof (and the amount of $186,438,767 defined as “Pro
 

 
  Forma Remaining Major Line Item Cost” in Section 2.2 of the P&S is deleted as beingof no operative effect in the P&S). 11. The parties acknowledge that the Study Period has expired. Purchaser shall perform itsobligations with respect to the remaining Deposit owing under Section 3.1 of the P&S.If, on or before 5:00 p.m. Boston time on November 10, 2006, Purchaser delivers to Seller aSurvey which Survey shows any matters that have a material and adverse effect on the value ordevelopment of the Property (“Materially Adverse Survey Matters”), such MateriallyAdverse Survey Matters are identified in reasonable detail in a notice of Purchaseraccompanying such Survey (“Survey Notice”) and such Materially Adverse Survey Matterswere not shown on that survey entitled “ALTA/ACSM Land Title Survey, Beth Israel DeaconessMedical Center, East Campus, Boston, Massachusetts, Issued For: Lyme Properties LLC”, preparedby Vanasse Haugen Brustlin, Inc., dated June 2, 2005, then Purchaser may in such Purchaser’sSurvey Notice unconditionally elect to terminate the P&S (subject to Seller’s rights as setforth hereafter). If Purchaser fails to timely and properly deliver such Survey Notice, thenthe provisions of this paragraph shall conclusively be deemed waived at 5:00 p.m. Boston timeon November 10, 2006. If Seller receives a Survey Notice, then Seller may within five (5)business days thereafter elect to attempt to cure the Materially Adverse Survey Matters bygiving written notice of such election to Purchaser, and Seller’s failure so to elect withinsuch time shall conclusively be deemed to be an election not to attempt to cure. If Seller soelects to cure, then Purchaser’s termination shall be suspended for up to sixty (60) dayswhile Seller attempts such cure. If within such time Seller so cures the Materially AdverseSurvey matters, then the Closing shall occur as provided in the P&S. If Seller elects (or isdeemed to have elected) not to cure such Materially Adverse Survey Matters, or if Sellerelects to cure and within such time Seller fails to cure such Materially Adverse SurveyMatters, then in either such case the suspension of Purchaser’s termination shall end, Sellershall receive Ten Million Dollars ($10,000,000) of the Deposit, the balance of the Depositshall be returned to Purchaser, and thereupon all obligations of the parties under the P&Sshall terminate without recourse except for the Surviving Obligations. 12. Section 6 of Schedule 8.2(e) to the P&S shall be deleted. At or before the Closing,Seller shall pay Contractor with respect to its claim on account of work performed to repairdamage to and around certain utility lines owned by MATEP that occurred as a result of anincident on or about June 23-24, 2006 (the “MATEP Repair Work”) so that Contractor reasonablyacknowledges full payment for, and satisfaction of the owner’s obligation with respect topayment for, the MATEP Repair Work. At the Closing, and thereafter, Purchaser shall reasonablycooperate with Seller in executing such instruments as Seller may reasonably request to allowSeller or its successors and assigns full power, right and standing to bring legal proceedingsagainst Berry and its subcontractors and sub-subcontractors and their respective insurers, andagainst the builders risk insurer of the Property, to recover for any losses or damages thatCLSB I has suffered as a result of the incident giving rise to the MATEP Repair Work,including those represented by payments made by Seller to Contractor; and notwithstandinganything in the P&S to the contrary any such claims are reserved to Seller, are not includedwithin the definition of
 

 
  Personal Property and are not being assigned to Purchaser. The provisions of this Sectionshall survive the Closing. 13. Purchaser will prepare and deliver to Seller an estoppel certificate as described in sectionVII of the Declaration of Easements, dated as of December 11, 1992, by The Beth IsraelHospital Association, a non-profit organization organized under M.G.L. c. 180, and recorded inthe Suffolk County Register of Deeds as document number 17945129. Seller shall promptlythereafter cause such estoppel certificate to be sent to the appropriate parties as designatedby Purchaser for execution and shall cooperate with Purchaser’s efforts to obtain suchexecuted estoppel certificate from such appropriate parties. 14. In all other respects the P&S is ratified and confirmed.      **IN WITNESS WHEREOF**, Seller and Purchaser hereto have executed this Amendment as of the datefirst written above.                     CLSB II, LLC joins in this agreement solely