**Exhibit 10.15 (b)**

**EXHIBIT A**

**AMENDED AND RESTATED SENIOR SECURED PROMISSORY NOTE**

**Cambridge, Massachusetts**
| **$7,000,000** | **As of  May 31, 2002** |
|----------------|-------------------------|

 

FOR VALUE RECEIVED,**DYAXCORP., a Delaware corporation (the “Debtor”), hereby promises to pay tothe order of GENZYME CORPORATION, a Massachusetts corporation (the “Lender”),the principal amount of SEVEN MILLION DOLLARS ($7,000,000), together withinterest on the unpaid principal balance of this Note from time to timeoutstanding at a variable rate per annum equal to the sum of: (a) the PrimeRate in effect from time to time and (b) two percent (2%) (the “Basic Rate”).  Each change in such interest rate shall takeeffect simultaneously with the corresponding change in such Prime Rate.  “Prime Rate” shall mean the rate of interestpublished in the *Wall Street Journal* as the primerate from time to time.  All interestaccrued hereunder shall be due and payable quarterly in arrears on the firstbusiness day of each calendar quarter, commencing on the first such date tooccur at least thirty (30) days after the date of the first advance.  The outstanding principal sum hereunder,together with any accrued but unpaid interest and all other charges payablehereunder, shall be due and payable in full on May 31, 2010 (the “MaturityDate”), unless accelerated or subject to mandatory prepayment as providedbelow.

Upon the occurrence of an Event of Default (asdefined below), the entire unpaid principal balance of this Note, together withany interest accrued thereon and all other sums due or owed by the Debtorhereunder, shall at the option of the Lender, upon notice from Lender (exceptfor an Event of Default under of Section 4(e) or Section 4(f) hereof which willbe without notice) to the Debtor become immediately due and payable withinterest (after such Event of Default and until the Debtor’s indebtedness tothe Lender is paid in full).  Interest onsuch amounts shall accrue and be payable at a rate per annum equal to the sumof:  (a) the sum of the Basic InterestRate then in effect and (b) three percent (3%).

All payments of principal, interest and other amountspayable on or in respect of this Note shall be made to the Lender at its officeat 500 Kendall Street, Cambridge, Massachusetts 02142, or to such other placeas the Lender may from time to time direct, in lawful money of the UnitedStates of America, in funds immediately available.  Interest shall be computed on the basis of a360-day year and a 30-day month.

It is the intent of the Lender and the Debtor that inno event shall interest be payable at a rate in excess of the maximum ratepermitted by applicable law (the “Maximum Legal Rate”).  Solely to the extent necessary to preventinterest under this Note from exceeding the Maximum Legal Rate, any amount thatwould be treated as excessive under a final judicial interpretation ofapplicable law shall be deemed to have been a mistake and automaticallycancelled and, if received by the Lender, shall be applied to the principalbalance of this Note or, if no principal balance remains outstanding, then suchamount shall be refunded to the Debtor.

1.             Collateral

This Note is secured by that certain letter of creditissued by Silicon Valley Bank, a copy of which is attached hereto as ExhibitA (the “Letter of Credit”) and incorporates by reference theprovisions thereof.  Neither theforegoing reference to the Letter of Credit nor any provisions thereof shallaffect or impair the absolute and unconditional obligation of the Debtor to paythe principal, interest and all other charges payable hereunder on this Note asprovided herein.

2.             [Intentionallyomitted.]

----

**EXHIBIT A**

3.             Prepayment of Principal

The Debtor may, at its option, prepay from time totime all or any part of this Note without premium or penalty but together withinterest on the principal amount so prepaid accrued to the date of prepayment.

4.             Events of Default

Upon the occurrence of any one or more of thefollowing events (each, an “Event of Default”), the Lender at its optionmay declare all amounts due hereunder, including, without limitation, theentire unpaid principal balance of this Note and any accrued, unpaid interestthereon, to be immediately due and payable without notice or protest (both ofwhich are hereby waived):

(a)           The failure to make any payment of interest within 5business days of the due date thereof (without reference to Section 6.3 below),or failure to make payment of principal or other amounts due pursuant to theterms of this Note on or before the due date;

(b)           A judgment, decree, writ, warrant of attachment or similarprocess in an amount equal to or exceeding $1,000,000 is entered against theDebtor or any of its assets, if such judgment, decree, writ, warrant ofattachment or similar process is not adequately covered by insurance or has notbeen vacated, discharged, appealed from (with execution or similar processcontinuously stayed) within thirty (30) days of such judgment’s entry;

(c)           The occurrence of any event that permits any indebtedness(including a capitalized lease obligation) of the Debtor equal to or exceeding$100,000 which is owed to a person or entity other than the Lender to beaccelerated, notwithstanding that such acceleration has not taken place;

(d)           A termination of the Amended and Restated CollaborationAgreement dated as of May 31, 2002, between the Debtor and the Lender, asamended to date (the “Collaboration Agreement”) by (i) either party pursuant toSections 13.2.3 or 13.2.4, (ii) the Debtor pursuant to Section 13.2.2, (iii)the Lender pursuant to Section 13.2.1 or (iv) either party pursuant to Section13.2.5 and the Debtor does not exercise its license optionpursuant to Section 13.3.5(a) of the Collaboration Agreement;

(e)           A proceeding is instituted in a court having jurisdictionin the premises seeking a decree or order for relief in respect to the Debtorin an involuntary case under any applicable bankruptcy, insolvency or othersimilar law nor or hereafter in effect, or for the appointment of a receiver,liquidator, assignee, custodian, trustee, sequestrator (or other similarofficial) of the Debtor, or for a substantial part of its property, or for thewinding-up or liquidation of it affairs, and such proceeding remainsundismissed or unstayed and in effect for a period of sixty (60) days or such courtenters a decree or order granting the relief sought in such proceeding;

(f)            The Debtor voluntarily suspends transaction of itsbusiness, dissolves or is liquidated, commences a voluntary case under anyapplicable bankruptcy, insolvency or other similar law now or hereafter ineffect, consents to the entry of an order for relief in an involuntary caseunder any such law, or consents to the appointment of or taking possession by areceiver, liquidator, assignee, trustee, custodian, sequestrator (or similarofficial) of the Debtor, as the case may be, or for any substantial part of itsproperty, or makes a general assignment for the benefit of creditors; or

(g)           The failure to provide Secured Party with theCompliance Certificate required by Section 7(c) below.

2

----

**EXHIBITI A**

Upon the occurrence of any Event of Defaulthereunder, (i) the Lender may declare the principal balance of this Note to beimmediately due and payable by written notice to the Debtor, *provided, however*, in thecase of an Event of Default described in paragraphs (e) or (f) above, allamounts payable by the Debtor hereunder, including, without limitation, theprincipal balance and all accrued interest on this Note, shall automaticallybecome immediately due and payable, without notice, action or election by theLender, and (ii) the Lender may enforce all other rights and remedies grantedpursuant to this Note, the Letter of Credit, any other document, or byapplicable law.  Without limitation, uponan Event of Default, Secured Party may draw upon the entire Letter ofCredit.  If the proceeds of the Letter ofCredit are insufficient to fully satisfy Debtor’s obligations under this Note,Debtor shall be fully liable for any deficiency.  All of the rights of the Lender hereundershall be cumulative and not exclusive, and each of which may be exercisedsingly, repetitively, in any combination, and in any order.  The Lender’s rights and remedies hereundermay be exercised without resort or regard to any other source of satisfactionof any liabilities owing by the Debtor to the Lender.  No inconsistency between the defaultprovisions of this Note and any other agreement shall be deemed to create anyadditional notice, cure or grace period or derogate from the express terms ofsuch provisions.

Upon the occurrence of an Event of Default, theDebtor agrees to pay on demand all costs and expenses (including, withoutlimitation, reasonable attorneys’ fees) incurred or paid by the Lender incollecting or enforcing this Note.

5.             Waiver

No delay or omission on the part of the Lender inexercising any right under this Note shall operate as a waiver of such right orof any other right of the Lender, nor shall any delay, omission or waiver onany one occasion be deemed a bar to or waiver of the same or any other right onany future occasion.  No course ofdealing or other conduct, no oral agreement or representation made by theLender or usage of trade shall operate as a waiver remedy of the Lender.  The Debtor, by executing this Note, and anyother makers, sureties, guarantors or endorsers, by endorsing this Note or byentering into or executing any agreement to pay any of the indebtednessevidenced hereby, waives (to the fullest extent allowed by law) allrequirements of diligence in collection, demand, presentment, notice ofnon-payment, protest, notice of protest, suit and all other conditionsprecedent in connection with the collection and enforcement of this Note or anysecurity for this Note or any guarantee of the indebtedness evidenced hereby(other than demand for payment if expressly required by this Note).  This Note shall be binding upon thesuccessors and assigns of the Debtor.

6.             General

6.1           Governing Law. This Note shall be governed by and construed in accordance with the lawsof the Commonwealth of Massachusetts.

6.2           Assignment. Neither the Lender nor the Debtor may assign its rights or obligationshereunder without the prior written consent of the other party.

6.3           Saturdays, Sundays, Holidays.  If any date that may at any time be specifiedin this Note as a date for the making of any payment on this Note shall fall onSaturday, Sunday or on a day which in the Commonwealth of Massachusetts shallbe a legal holiday, then the date for the making of that payment shall be thenext subsequent day which is not a Saturday, Sunday or legal holiday.

6.4           Notices. Except in the case of notices and other communications expresslypermitted to be given by telephone, all notices and other communicationsprovided for herein shall be in writing and shall be delivered by hand orovernight courier service, mailed by certified or registered mail or sent bytelecopy, as follows:

3

----

**EXHIBIT A**

(a)                                   if to the Lender, to Genzyme Corporation, 500Kendall Street, Cambridge, MA  02142,Attn: Mr. Michael Wyzga, Telephone: (617) 252-7500, Facsimile: (617) 252-7802;with a copy to:  Genzyme Corporation, OneKendall Square, Cambridge, Massachusetts 02139-1562, Attn: Chief Legal Officer,Telephone: (617) 252-7500, Facsimile: (617) 252-7553; and

(b)                                  if to the Debtor, to Dyax Corp., 300 TechnologySquare, Cambridge, Massachusetts 02139, Attention:  Chief Financial Officer, Telephone: (617)225-2500, Facsimile: (617) 225-2501), with a copy to:  Dyax Corp., 300 Technology Square, Cambridge,Massachusetts 02139, Attention: Corporate Counsel, Telephone: (617) 225-2500,Facsimile: (617) 225-2501).

6.5           Entire Agreement. This Note, together with the Letter of Credit and the CollaborationAgreement, contains the entire agreement between the parties with respect tothe subject matter hereof, and supersedes every course of dealing, otherconduct, oral agreement or representation previously made by the Lender.  All prior agreements between the Debtor andthe Lender concerning the lending and borrowing of money are hereby terminated.

6.6           Severability. In the event that any court of competent jurisdiction shall determinethat any provision, or portion thereof, contained in this Note shall beunenforceable in any respect, then such provision shall be deemed limited tothe extent that such court deems it enforceable, and the remaining provisionsof this Note shall nevertheless remain in full force and effect.

6.7           Amendments. None of the terms or provisions of this Note may be excluded, modified,or amended except by a written instrument duly executed on behalf of both theDebtor and the Lender expressly referring hereto and setting forth theprovision so excluded, modified or amended. No waiver or forbearance of any of the rights and remedies of the Lenderhereunder shall be effective unless made specifically in a writing signed bythe Lender, and any such waiver or forbearance shall be effective only in thespecific instance and for the specific purpose for which given.

6.8           Headings. The headings in this Note are for convenience only and shall not affectthe interpretation hereof.

6.9           Amends and Restates.  This Note amends, restates and replaces inits entirety that certain Senior Secured Promissory Note dated May 31, 2002,made by the Debtor to the order of the Lender in the original, principal amountof $7,000,000.

7.             AdditionalProvisions.

(a)           Representationsand Warranties.  Debtor hereby representsand warrants that:

(i)                                     no claim, litigation or proceeding isthreatened or pending which would have a material adverse effect on the Debtor;and

(ii)                                  all indebtedness (as defined by GAAP) ofDebtor existing as of July 31, 2006 is accurately described in Schedule Aattached hereto and the Company has not incurred any material indebtednesssince July 31, 2006.

(b)           FinancialReports.  Debtor will deliver to theSecured Party (i) as soon as available, but no later than one hundred twenty(120) days after the last day of the Debtor’s fiscal year, audited consolidatedfinancial

4

----

**EXHIBIT A**

statementsprepared under GAAP, together with an unqualified opinion on the financialstatements from an independent certified public accounting firm reasonablyacceptable to the Secured Party, and (ii) within five (5) days of the filing,copies of all statements, reports and notices made available to Debtor’ssecurity holders and all reports on Form 10-K, 10-Q and 8-K filed with theSecurities and Exchange Commission.

(c)           MonthlyCompliance.  No later than five (5)days after the end of each calendar quarter, Debtor shall provide to SecuredParty a quarterly compliance certificate in the form of Exhibit Battached hereto (the “Compliance Certificate”).

IN WITNESS WHEREOF, the undersigned has executed this Note under seal asof August  23, 2006, to be effective as of May 31, 2002.
|   | DYAX CORP.                                   |
|--------|----------------------------------------------|
|   |                                         |
|   |                                         |
|   | By                                           | /s/ Thomas R.  Beck |   |
|   | Name: Thomas R. Beck                         |
|   | Title: President and Chief Operating Officer |

 
| By its signature below, the  Lender acknowledges the terms of    |                  |   |
|------------------------------------------------------------------|-----------------------|--------|
| this Note and  agrees to be bound by the provisions of this Note |                  |   |
| applicable to  the Lender:                                       |                  |   |
|                                                             |                  |   |
| GENZYME  CORPORATION                                             |                  |   |
|                                                             |                  |   |
|                                                             |                  |   |
| By                                                               | /s/ Michael S.  Wyzga |   |   |   |
| Name: Michael S. Wyzga                                           |                  |   |
| Title: CFO                                                       |                  |   |
|                                                                  |                       |        |  |  |

 

5

----