Document:

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                                                                    Exhibit 10.2

                         SENIOR SECURED PROMISSORY NOTE

                                                       Cambridge, Massachusetts
$7,000,000                                                         May 31, 2002

         FOR VALUE RECEIVED, DYAX CORP., a Delaware corporation (the "Debtor"),
hereby promises to pay to the order of GENZYME CORPORATION, a Massachusetts
corporation (the "Lender"), the principal balance of SEVEN MILLION DOLLARS
($7,000,000) or such lesser amount as shall have been advanced to the Debtor
hereunder, together with interest on the unpaid principal balance of this Note
from time to time outstanding at a variable rate per annum equal to the sum of:
(a) the Prime Rate in effect from time to time and (b) two percent (2%) (the
"Basic Rate"). Each change in such interest rate shall take effect
simultaneously with the corresponding change in such Prime Rate. "Prime Rate"
shall mean the rate of interest published in the WALL STREET JOURNAL as the
prime rate from time to time. All interest accrued hereunder shall be due and
payable quarterly in arrears on the first business day of each calendar quarter,
commencing on the first such date to occur 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 payable hereunder,
shall be due and payable in full on May 31, 2005 (the "Maturity Date"), unless
accelerated or subject to mandatory prepayment as provided below.
Notwithstanding the foregoing Maturity Date, unless accelerated or subject to
mandatory prepayment as provided below, the term of this Note may be extended by
the Debtor until May 31, 2007 (the "New Maturity Date") if on the Maturity Date,
Debtor has met the conditions described in Schedule A attached hereto.

         Upon the occurrence of an Event of Default (as defined below), the
entire unpaid principal balance of this Note, together with any interest accrued
thereon and all other sums due or owed by the Debtor hereunder or under the
terms of that certain Security Agreement dated as of even date with this Note
between the Debtor and the Lender (the "Security Agreement"), shall at the
option of the Lender, upon notice from Lender (except for an Event of Default
under of Section 4(f) or Section 4(g) hereof which will be without notice) to
the Debtor become immediately due and payable with interest (after such Event of
Default and until the Debtor's indebtedness to the Lender is paid in full) at a
rate per annum equal to the sum of: (a) the sum of the Basic Rate and (b) three
percent (3%).

         All payments of principal, interest and other amounts payable on or in
respect of this Note shall be made to the Lender at its office at One Kendall
Square, Cambridge, Massachusetts 02139, or to such other place as the Lender may
from time to time direct, in lawful money of the United States of America, in
funds immediately available. Interest shall be computed on the basis of a
360-day year and a 30-day month.

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         It is the intent of the Lender and the Debtor that in no event shall
interest be payable at a rate in excess of the maximum rate permitted by
applicable law (the "Maximum Legal Rate"). Solely to the extent necessary to
prevent interest under this Note from exceeding the Maximum Legal Rate, any
amount that would be treated as excessive under a final judicial interpretation
of applicable law shall be deemed to have been a mistake and automatically
cancelled and, if received by the Lender, shall be applied to the principal
balance of this Note or, if no principal balance remains outstanding, then such
amount shall be refunded to the Debtor.

         Notwithstanding any provision of this Note to the contrary, if the
Debtor at any time has $100,000,000 or more in cash or cash equivalents as
reported in the Debtor's consolidated financial statements filed with the
Securities and Exchange Commission, then the Lender shall be entitled at its
option to require the Debtor to prepay in full all amounts due hereunder, by
providing the Debtor with thirty (30) days' prior written notice of such
mandatory prepayment, in which case, all outstanding principal, any accrued but
unpaid interest and all other charges due hereunder shall become due and payable
on the thirtieth (30th) day following such notice.

1.       DESCRIPTION OF NOTE; ADVANCES

         This Note is secured by the Collateral granted pursuant to the Security
Agreement and incorporates by reference the provisions thereof. Neither the
foregoing reference to the Security Agreement nor any provisions thereof shall
affect or impair the absolute and unconditional obligation of the Debtor to pay
the principal, interest and all other charges payable hereunder on this Note as
provided herein.

         Subject to the terms and conditions set forth herein and at any time
prior to the Maturity Date (except as provided below), the Debtor may, by
delivering written notice to the Lender prior to the date of the requested
advance, request an advance hereunder in a minimum principal amount of not less
than two hundred fifty thousand dollars ($250,000). The Lender shall make such
advance on or before the twentieth business day following receipt of such
notice. Advances may be made once each calendar quarter, beginning on the date
hereof and ending upon completion of the first Phase II clinical trial, either
in the United States or Europe, of a Collaboration Product for the treatment of
HAE, as such terms are defined in that certain Amended and Restated
Collaboration Agreement dated as of the date hereof between the Debtor and the
Lender (the "Collaboration Agreement"). The Lender shall not be obligated to
make advances in excess of $4,000,000 during the second quarter of 2002 and
$1,500,000 during any subsequent calendar quarter. Notwithstanding any provision
of this Note to the contrary, the Lender shall have no obligation to make any
advances hereunder if a Default (as defined below) or an Event of Default
exists. For purposes of this Note, a "Default" means an event or circumstance
which, with the giving of notice, the passage of time, or both, would constitute
an Event of Default.

         Notwithstanding any provision of this Note or the Collaboration
Agreement to the contrary, upon the effective date of any termination of the
Collaboration Agreement by (i) the Lender in accordance with Section 13.2.2,
(ii) the Debtor in accordance with Section 13.2.1 or (iii) either party in
accordance with Section 13.2.5 thereof AND Dyax exercises its license option
pursuant to Section 13.3.5(a) of the Collaboration Agreement, the Lender shall
have no further obligation to make any further advances under this Note.
Additionally, notwithstanding any

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provision of this Note or the Collaboration Agreement to the contrary, upon the
effective date of any termination of the Collaboration Agreement by (i) either
party pursuant to Sections 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 Section 13.2.5 AND Dyax does NOT exercise its license option
pursuant to Section 13.3.5(a) of the Collaboration Agreement, all amounts
outstanding hereunder on the effective date of such termination shall become
immediately due and payable without notice or further action by the Lender.

         The date and amount of all advances made by the Lender to the Debtor
hereunder and each payment made by the Debtor on account of the principal
balance hereof, shall be recorded by the Lender on its books and, prior to any
transfer of this Note, recorded by the Lender on the schedule attached hereto or
any continuation thereof; PROVIDED that the failure of the Lender to make any
such recordation shall not affect the obligations of the Debtor to make a
payment when due of any amount owing hereunder with respect to any advances made
by the Lender.

2.       [Intentionally omitted.]

3.       PREPAYMENT OF PRINCIPAL

         The Debtor may, at its option, prepay from time to time all or any part
of this Note without premium or penalty but together with interest 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 the following events (each,
an "Event of Default"), the Lender at its option may declare all amounts due
hereunder, including, without limitation, the entire unpaid principal balance of
this Note and any accrued, unpaid interest thereon, to be immediately due and
payable without notice or protest (both of which are hereby waived):

                (a) The failure to make any payment of interest within 5
business 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 the
terms of this Note or the Security Agreement on or before the due date;

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

                (c) The occurrence of any event that causes 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 be
accelerated, notwithstanding that such acceleration has not taken place;

                (d) The occurrence of an Event of Default under the Security
Agreement;

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                (e) A termination of the Collaboration Agreement by (i) either
party pursuant to Sections 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 Section 13.2.5 AND Dyax does NOT exercise its license option
pursuant to Section 13.3.5(a) of the Collaboration Agreement;

                (f) A proceeding is instituted in a court having jurisdiction in
the premises seeking a decree or order for relief in respect to the Debtor in an
involuntary case under any applicable bankruptcy, insolvency or other similar
law nor or hereafter in effect, or for the appointment of a receiver,
liquidator, assignee, custodian, trustee, sequestrator (or other similar
official) of the Debtor, or for a substantial part of its property, or for the
winding-up or liquidation of it affairs, and such proceeding remains undismissed
or unstayed and in effect for a period of sixty (60) days or such court enters a
decree or order granting the relief sought in such proceeding; or

                (g) The Debtor voluntarily suspends transaction of its business,
dissolves or is liquidated, commences a voluntary case under any applicable
bankruptcy, insolvency or other similar law now or hereafter in effect, consents
to the entry of an order for relief in an involuntary case under any such law,
or consents to the appointment of or taking possession by a receiver,
liquidator, assignee, trustee, custodian, sequestrator (or similar official) of
the Debtor, as the case may be, or for any substantial part of its property, or
makes a general assignment for the benefit of creditors.

         Upon the occurrence of any Event of Default hereunder, (i) the Lender
may declare the principal balance of this Note to be immediately due and payable
by written notice to the Debtor, PROVIDED, however, in the case of an Event of
Default described in paragraphs (f) or (g) above, all amounts payable by the
Debtor hereunder, including, without limitation, the principal balance and all
accrued interest on this Note, shall automatically become immediately due and
payable, without notice, action or election by the Lender, and (ii) the Lender
may enforce all other rights and remedies granted pursuant to this Note, the
Security Agreement, any other document, or by applicable law. All of the rights
of the Lender hereunder shall be cumulative and not exclusive, and each of which
may be exercised singly, repetitively, in any combination, and in any order. The
Lender's rights and remedies hereunder may be exercised without resort or regard
to any other source of satisfaction of any liabilities owing by the Debtor to
the Lender. No inconsistency between the default provisions of this Note and any
other agreement shall be deemed to create any additional notice, cure or grace
period or derogate from the express terms of such provisions.

         Upon the occurrence of an Event of Default, the Debtor agrees to pay on
demand all costs and expenses (including, without limitation, reasonable
attorneys' fees) incurred or paid by the Lender in collecting or enforcing this
Note.

5.       WAIVER

         No delay or omission on the part of the Lender in exercising any right
under this Note shall operate as a waiver of such right or of any other right of
the Lender, nor shall any delay, omission or waiver on any one occasion be
deemed a bar to or waiver of the same or any other right on any future occasion.
No course of dealing or other conduct, no oral agreement or

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representation made by the Lender or usage of trade shall operate as a waiver
remedy of the Lender. The Debtor, by executing this Note, and any other makers,
sureties, guarantors or endorsers, by endorsing this Note or by entering into or
executing any agreement to pay any of the indebtedness evidenced hereby, waives
(to the fullest extent allowed by law) all requirements of diligence in
collection, demand, presentment, notice of non-payment, protest, notice of
protest, suit and all other conditions precedent in connection with the
collection and enforcement of this Note or any security 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 the successors
and assigns of the Debtor.

6.       GENERAL

         6.1 GOVERNING LAW. This Note shall be governed by and construed in
accordance with the laws of the Commonwealth of Massachusetts.

         6.2 ASSIGNMENT. Neither the Lender nor the Debtor may assign its rights
or obligations hereunder without the prior written consent of the other party.

         6.3 SATURDAYS, SUNDAYS, HOLIDAYS. If any date that may at any time be
specified in this Note as a date for the making of any payment on this Note
shall fall on Saturday, Sunday or on a day which in the Commonwealth of
Massachusetts shall be a legal holiday, then the date for the making of that
payment shall be the next subsequent day which is not a Saturday, Sunday or
legal holiday.

         6.4 NOTICES. All notices hereunder shall be made in accordance with
Section 20 of the Security Agreement.

         6.5 ENTIRE AGREEMENT. This Note, together with the Security Agreement
and the Collaboration Agreement, contains the entire agreement between the
parties with respect to the subject matter hereof, and supersedes every course
of dealing, other conduct, oral agreement or representation previously made by
the Lender. All prior agreements between the Debtor and the Lender concerning
the lending and borrowing of money are hereby terminated.

         6.6 SEVERABILITY. In the event that any court of competent jurisdiction
shall determine that any provision, or portion thereof, contained in this Note
shall be unenforceable in any respect, then such provision shall be deemed
limited to the extent that such court deems it enforceable, and the remaining
provisions of 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 the Debtor and the Lender expressly referring hereto and setting
forth the provision so excluded, modified or amended. No waiver or forbearance
of any of the rights and remedies of the Lender hereunder shall be effective
unless made specifically in a writing signed by the Lender, and any such waiver
or forbearance shall be effective only in the specific instance and for the
specific purpose for which given.

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         6.8 HEADINGS. The headings in this Note are for convenience only and
shall not affect the interpretation hereof.

         IN WITNESS WHEREOF, the undersigned has executed this Note under seal
as of the date first above written.

                                           DYAX CORP.

                                           By /s/ Jack Morgan
                                              ---------------------------------
                                              Name:  Jack Morgan
                                              Title: Senior Vice President

By its signature below, the Lender agrees
to make advances under this Note in accordance
with the provisions herein:

GENZYME CORPORATION

By /s/ G. Jan Van Heek
   ------------------------------
  Name:  G. Jan Van Heek
  Title: Executive Vice President

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SCHEDULE OF LOANS

         This Note evidences loans made on the dates and in the principal
amounts set forth below, subject to the payments or prepayments set forth below:

<TABLE>
<CAPTION>

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                              Principal           Amount Paid or        Unpaid Principal
        Date Made           Amount of Loan            Prepaid                Amount            Notation Made By
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<S>                       <C>                  <C>                    <C>                    <C>
                            $                      $                     $
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</TABLE>

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                                   SCHEDULE A

                              EXTENSION CONDITIONS

1.       The Collaboration Agreement shall be in full force and effect.

2.       The Debtor satisfies the financial covenants set forth in Section 7A of
         the Security Agreement as of the Maturity Date.

3.       No Default or Event of Default exists.

                                       8<PAGE>

                                                                    Exhibit 10.3

                               SECURITY AGREEMENT

         This Security Agreement (this "AGREEMENT") dated as of May 31, 2002 is
between DYAX CORP., a Delaware corporation with its principal place of business
at 300 Technology Square, Cambridge, Massachusetts 02139 (the "DEBTOR") and
GENZYME CORPORATION, a Massachusetts corporation with its principal place of
business at One Kendall Square, Cambridge, Massachusetts 02139 (THE "SECURED
PARTY").

                                    RECITALS

         WHEREAS, the Secured Party has agreed to loan Debtor the principal sum
of up to seven million dollars ($7,000,000), the repayment of which, together
with interest and other charges, shall be evidenced by that Senior Secured
Promissory Note dated the date hereof (the "NOTE"); and

         WHEREAS, the Secured Party's agreement to advance funds pursuant to the
Note is conditioned upon, among other things, the Debtor providing security for
the payment of the Note;

         NOW, THEREFORE, in consideration of the loan and for other good and
valuable consideration, receipt and sufficiency of which are hereby
acknowledged, the parties agree as follows:

         1. DEFINITIONS.

         As used in this Agreement, the following terms have the following
meanings:

         "Default" means an event or circumstance which, with the giving of
notice, the passage of time, or both, could constitute an Event of Default.

         "GAAP" means generally accepted accounting principles as in effect in
the United States of America from time to time, consistently applied.

         "Indebtedness" means (a) all obligations for borrowed money or the
deferred price of property or services, such as reimbursement and other
obligations for surety bonds and letters of credit, (b) obligations evidenced by
notes, bonds, debentures or similar instruments, (c) capital lease obligations,
(d) all obligations or liabilities of others that are guaranteed and (e) any
other obligations or liabilities which are required by GAAP to be shown as debt
on a balance sheet.

         "Intellectual Property" means all of the Debtor's right, title and
interest in and to patents, patent rights, trademark licenses, trademarks,
service marks and copyrights (and applications and registrations therefore
including all reissues, divisions, continuations, extensions and
continuations-in-part thereof), inventions, improvements, discoveries, data,
know-how, methods, processes, whether or not patentable, including but not
limited to formulations, techniques and

<PAGE>

materials, analytical data, clinical data, manufacturing know-how and
processing, purification and fill-finish know-how, master file, control
information, all regulatory information, permits, licenses, trade names, trade
styles, bioinformatics, trade secrets, drawings, specifications, descriptions,
and all memoranda, notes, and records with respect to any research and
development, all whether now owned or subsequently acquired or developed by the
Debtor and whether in tangible or intangible form or contained on magnetic media
readable by machine together with all such magnetic media.

         "Letter of Credit" shall mean a letter of credit (a) issued by a bank
satisfactory in all respects to the Secured Party, (b) in an amount equal to (i)
the amount of the then-outstanding balance under the Note, if the principal
amount of the Note has been fully advanced or (ii) the amount of the
then-outstanding balance under the Note, plus the amount of remaining advances
to be made, if the Note has not yet been fully advanced, (c) that has an
expiration date not earlier than 30 days after the Maturity Date or New Maturity
Date, both as applicable and as defined in the Note, and (d) that otherwise
contains terms in all respects satisfactory to the Secured Party including,
without limitation, the right of Secured Party to draw down thereon immediately
upon an Event of Default.

         "Lien" is a mortgage, lien, deed of trust, charge, pledge, security
interest or other encumbrance.

         "Program" means the Debtor's research, development, production and
sales relating to human plasma Kallikrein inhibitors, including that certain
58-amino acid polypeptide human plasma Kallikrein inhibitor known as "DX-88"
(formerly known as EPI-KAL-2) together with all analogs, homologs, derivatives
and improvements related thereto.

         "Permitted Indebtedness" is:

            (1) Debtor's Indebtedness to the Secured Party under the Note or
this Agreement;

            (2) Indebtedness existing as of the date hereof and shown on
Schedule B attached hereto;

            (3) Indebtedness to trade creditors incurred in the ordinary course
of business; and

            (4) other Indebtedness of the Debtor and its subsidiaries consisting
of capital lease obligations or purchase money security obligations secured only
by Liens permitted under clause (d) of the definition of "Permitted Liens," in
an aggregate principal amount not in excess of $15,000,000 at any one time
outstanding;

            (5) Indebtedness that is subordinated to Debtor's Indebtedness to
the Secured Party, pursuant to subordination provisions satisfactory to the
Secured Party.

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         "Permitted Liens" are:

            (a) Liens existing as of the date hereof and shown on Schedule B
attached hereto or arising under this Agreement;

            (b) Liens in favor of the Lender arising under this Agreement; and

            (c) Liens for taxes, fees, assessments or other government charges
or levies, either not delinquent or being contested in good faith and for which
the Debtor maintains adequate reserves on its books, IF they have no priority
over any of Secured Party's security interests.

            (d) Liens on fixed or capital assets, including personal property,
acquired, constructed or improved by any of the Debtor and its subsidiaries,
provided that (A) such Liens secure Indebtedness (including capital lease
obligations) permitted by clause (4) of the definition of "Permitted
Indebtedness," (B) such Liens and the Indebtedness secured thereby are incurred
prior to or within 90 days after such acquisition or the completion of such
construction or improvement, (C) the Indebtedness secured thereby does not
exceed the cost of acquiring, constructing or improving such fixed or capital
assets, and (D) such security interests shall not apply to any other property or
assets of any of the Debtor or its subsidiaries; and

         "UCC" means the Uniform Commercial Code as in effect from time to time
in any applicable jurisdiction, as the same may be amended from time to time.

         2. GRANT.

            (a) COLLATERAL. To secure the full and prompt payment and
performance of the Obligations (as defined below), the Debtor grants the Secured
Party a continuing security interest in all of the Debtor's right, title and
interest in and to the following property of or arising from the Program,
whether now owned or existing or hereafter acquired or arising: all tangible and
intangible personal property of or arising from the Program, including, but not
limited to, the following (i): all goods, accounts, and general intangibles (as
those terms are defined in the UCC), (ii) all Intellectual Property of or
arising from the Program including, but not limited to, the patents issued or
assigned to and all patent applications made by the Debtor relating to human
plasma Kallikrein inhibitors, including that certain 58-amino acid polypeptide
human plasma Kallikrein inhibitor known as "DX-88" (formerly known as
EPI-KAL-2), including, without limitation, the patents, patent applications and
exclusive licenses listed on SCHEDULE A hereto; (iii) all infringement claims
with regard to such Intellectual Property; (iv) all rights to income, profits,
royalties, damages, licenses or other rights related to such Intellectual
Property; and (v) all proceeds (as defined by the UCC) and products of the
foregoing (collectively, the "COLLATERAL"). Notwithstanding anything to the
contrary, Debtor does not pledge any assets that are not specific to or that do
not arise from the Program; nor does the Collateral include any equipment. Upon
Debtor's exercise of the Surgical Product Option in Section 3.2 of the Amended
and Restated Collaboration Agreement dated as of May 31, 2002 by and between the
parties hereto (the "Collaboration Agreement"), so long as no Default or Event
of Default exists, Secured Party shall release its security interest in that
portion of the Collateral that relates to the Surgical Products indication and
add as collateral the Additional Collateral as set forth below in Section 2(b).

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            (b) ADDITIONAL COLLATERAL. Upon (i) Debtor's exercise of the
Surgical Product Option in Section 3.2 of the Collaboration Agreement, (ii)
Debtor's breach of the financial covenant set forth in Section 7A(a) hereof, or
(iii) Debtor's breach of the financial covenant set forth in Section 7A(b)
hereof, Debtor shall add as additional collateral (i) the Applicable Percentage
(as hereafter defined) of all of Debtor's right, title and interest in Debtor's
ownership interest in Biotage, Inc. (the "Shares"); (ii) all products, proceeds,
substitutions, additions, interest, dividends and other distributions
(including, without limitation, stock splits) relating to the shares and (iii)
all books and records relating to the property described in (i) and (ii)
(collectively, the "Additional Collateral"). Thereafter, all references in this
Agreement to the "Collateral" shall be deemed to include the Additional
Collateral. Effective upon the occurrence of any of the events set forth in this
Section 2(b) above, to further secure the full and prompt payment and
performance of the Obligations, the Debtor grants the Secured Party a continuing
security interest in all of the Debtor's right, title and interest in and to the
Additional Collateral. No later than five days after the occurrence of any of
the events set forth in this Section 2(b) above, the Debtor shall execute a
stock pledge agreement in form and substance reasonably satisfactory to the
Secured Party and deliver to the Secured Party related stock certificates and
stock powers and failure to do so shall constitute an Event of Default. The
Secured Party agrees that the Debtor shall no longer be obligated to grant the
Secured Party the Additional Collateral or, if such Additional Collateral has
already been granted, shall release such Additional Collateral, after the
Secured Party confirms that it has been provided with a Letter of Credit.

         "Applicable Percentage" shall mean (a) forty-nine percent (49%) in the
event of (i) Debtor's exercise of the Surgical Product Option in Section 3.2 of
the Collaboration Agreement or (ii) Debtor's breach of the financial covenant
set forth in Section 7A(a) hereof and (b) sixty-seven percent (67%) in the event
of Debtor's breach of the financial covenant set forth in Section 7A(b) hereof.

         3. OBLIGATIONS. The security interest granted in Section 2 above
secures all payment and performance obligations of the Debtor to the Secured
Party under the terms of the Note and this Agreement (collectively, the
"OBLIGATIONS").

         4. REPRESENTATIONS, WARRANTIES AND COVENANTS. The Debtor hereby
represents, warrants, covenants and agrees as follows:

            (a) the Debtor is a corporation duly organized, validly existing and
in good standing under the laws of the State of Delaware. The Debtor's exact
legal name is that indicated on page 1 and on the signature page of this
Agreement. The Debtor's tax identification number is 04-3053198. Biotage, Inc.
is a corporation duly organized, validly existing and in good standing under the
laws of Delaware and is a wholly-owned subsidiary of the Debtor. The execution,
delivery and performance of this Agreement by the Debtor has been duly
authorized by all necessary corporate action and does not contravene the
Debtor's Certificate of Incorporation or By-Laws as currently in effect;

            (b) neither the execution, delivery or performance by the Debtor of
this Agreement or the consummation by the Debtor of the transactions
contemplated hereby or thereby will result in a violation or breach of (or give
rise to any right of termination, revocation, cancellation or acceleration under
or increased payments under), or constitute a default (with or

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without due notice or lapse of time or both) under, or result in the creation of
any Lien, upon any of the properties or assets of the Debtor under, any of the
terms, conditions or provisions of any note, bond, mortgage, indenture,
contract, agreement, obligation, instrument, offer, commitment, understanding or
other arrangement or of any license, waiver, exemption, order, franchise, permit
or concession to which the Debtor is a party or by which any of its properties
or assets is bound;

            (c) the security interest granted to the Secured Party in the
Collateral shall constitute a first lien, and that the Debtor is the lawful
owner of such Collateral free from any right or claim of any person or any Lien,
and has good right to pledge, sell, consign, assign, transfer and create a
security interest in the same. The patents, patent applications and exclusive
licenses listed on SCHEDULE A hereto constitute all such property included in
the Program that the Debtor owns or has an interest in as of the date hereof;

            (d) the Collateral is and will be used primarily for business
purposes and will not be held for sale or leased to others, or otherwise
disposed of by the Debtor without the prior written consent of the Secured
Party. Additionally, unless and until Debtor exercises the Surgical Product
Option in Section 3.2 of the Collaboration Agreement as described in Section 2
(a) above, the Debtor shall not be entitled to grant any licenses of any of its
Intellectual Property related to the Program to third parties;

            (e) the tangible Collateral is located at 300 Technology Square,
Cambridge, MA 02139. Other than in the ordinary course of business, the
Collateral will not be removed from this location without prior written notice
to the Secured Party.

            (f) without the prior written consent of the Secured Party, the
Debtor will not grant or permit to exist any security interest in, or any lien,
attachment, levy or encumbrance upon, any of the Collateral or the Additional
Collateral, except for Permitted Liens;

            (g) the Debtor will not, without the prior written consent of the
Secured Party, execute (or authorize the filing of) any financing statements or
other documents evidencing a lien in connection with the Collateral other than
those in favor of the Secured Party;

            (h) no claim, litigation or proceeding is threatened or pending
which would have a material adverse effect on the Debtor or ownership or value
of the Collateral;

            (i) all Indebtedness of Debtor existing as of the date hereof is
accurately described in Schedule B attached hereto; and

            (j) as of the date hereof, there are no Liens on any of the Debtor's
personal property, except as set forth in Schedule B attached hereto.

         5. COVENANTS CONCERNING DEBTOR'S LEGAL STATUS. The Debtor covenants
with the Secured Party as follows: (a) without providing at least thirty (30)
days' prior written notice to the Secured Party, the Debtor will not change its
name, its chief executive office, its mailing address, tax identification number
or organizational identification number, if it has one, (b) if the Debtor does
not have an organizational identification number and later obtains one, the
Debtor will forthwith notify the Secured Party of such organizational
identification number, and (c)

                                       5
<PAGE>

without providing at least thirty (30) days' prior written notice to Secured
Party, the Debtor will not change its type of organization, jurisdiction of
organization or other legal structure.

         6. PROTECTION OF COLLATERAL. For so long as this Agreement is in
effect, the Debtor will:

            (a) comply with all laws, ordinances and regulations to which it is
subject and use the Collateral in a lawful manner and not in contravention of
the requirements of any policy of insurance;

            (b) keep all property insured with such insurance companies and in
such amounts and coverages as are reasonably satisfactory to the Secured Party.
The Secured Party shall be named as a loss payee and an additional insured as
its interest may appear on all insurance applicable to the Collateral. The
Debtor shall furnish the Secured Party with certificates or other evidence of
insurance satisfactory to the Secured Party within thirty (30) days of the date
of this Agreement. All evidence of insurance shall also provide for at least
thirty (30) days' prior notice to the Secured Party of any cancellation,
modification, or change in coverage. Any insurance proceeds received by the
Secured Party may be, at its option, applied to the Obligations.

            (c) pay all taxes, liens, and assessments when due, except for the
lien of property taxes not yet due and payable and except for the payment of any
taxes which are being contested in good faith by the Debtor and for which
adequate reserves have been set aside;

            (d) maintain the collateral in good order and repair (reasonable
wear and tear excepted) at the Debtor's addresses set forth in Section 4(e). The
Collateral and the Additional Collateral will not be encumbered, sold, assigned,
or otherwise transferred, whether voluntarily or by operation of law, except for
the sale of inventory in the ordinary course of business, without the prior
written consent of the Secured Party;

            (e) keep and maintain the Collateral in accordance with all
applicable laws, rules and regulations (governmental and otherwise);

            (f) keep complete and accurate records of all Collateral. The
Secured Party may inspect and copy such records and inspect the Collateral at
any time, without prior notice, during normal business hours;

            (g) execute, at the Secured Party's request, such documents which
the Secured Party deems necessary to protect and perfect its security interest
and other rights in the Collateral. Debtor also grants the Secured Party an
irrevocable power of attorney to execute all such documents on Debtor's behalf.

         7. ADDITIONAL COVENANTS. For so long as this Agreement is in effect,
the Debtor:

            (a) will not, and will not permit any of its subsidiaries to,
without the Secured Party's prior written consent, create, incur, assume or be
liable for any Indebtedness, other than Permitted Indebtedness;

                                       6
<PAGE>

            (b) will not, without the Secured Party's prior written consent,
create, incur or allow any Lien on any of the Collateral or the Additional
Collateral, except for Permitted Liens listed in clauses (b) and (c) in the
definition of "Permitted Liens";

            (c) will not, without the Secured Party's prior written consent,
merge or consolidate with any person or entity or acquire all or substantially
all of the capital stock or assets of any person or entity;

            (d) will deliver to the Secured 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 consolidated financial statements prepared under GAAP,
together with an unqualified opinion on the financial statements from an
independent certified public accounting firm reasonably acceptable to the
Secured Party, and (ii) within five (5) days of the filing, copies of all
statements, reports and notices made available to Debtor's security holders and
all reports on Form 10-K, 10-Q and 8-K filed with the Securities and Exchange
Commission; and

            (e) will not, without the Secured Party's prior written consent,
directly or indirectly transfer any of its interest in Biotage, Inc. or permit
Biotage, Inc. to transfer any of its assets, except in the ordinary course of
business, unless the Secured Party confirms that it has been provided with a
Letter of Credit.

         7A. FINANCIAL COVENANTS.

             (a) The Debtor (and its subsidiaries) shall not at any time have
less than $20,000,000 in cash or cash equivalents which shall be determined
quarterly based on its consolidated balance sheet filed with the Securities and
Exchange Commission.

             (b) The Debtor shall maintain at least one continued listing
standard for the Nasdaq National Market.

             (c) The Debtor shall immediately notify the Secured Party of the
Debtor's failure to comply with Section 7A(a) or Section 7A(b) above.

         8. REIMBURSEMENT. In the event Debtor fails to obtain any insurance or
pay any tax, lien or assessment which it is required to obtain or pay (except to
the extent such nonpayment is permitted under Section 6(c) above) or otherwise
perform any obligation under this Agreement, the Secured Party may, at its
option, obtain, pay or otherwise perform the same on the Debtor's behalf. In
such event, the cost together with interest from the date of payment by the
Secured Party at the rate of ten percent (10%) per annum shall be included as an
Obligation and shall be due and payable upon demand by the Secured Party. The
Secured Party shall have no obligation to make any such expenditures, nor shall
the making thereof be construed as a waiver or cure of any Event of Default.

         9. AUTHORIZATION TO FILE FINANCING STATEMENTS. The Debtor hereby
irrevocably authorizes the Secured Party at any time and from time to time to
file in any filing office in any UCC jurisdiction any initial financing
statements and amendments thereto that (a) indicate the Collateral and (b)
provide any other information required by part 5 of Article 9 of the UCC for the
sufficiency or filing office acceptance of any financing statement or amendment,
including

                                       7
<PAGE>

whether the Debtor is an organization, the type of organization and any
organization identification number issued to the Debtor. The Debtor agrees to
furnish any such information to the Secured Party promptly upon the Secured
Party's request.

         10. EVENTS OF DEFAULT. The happening of any of the following shall be
an Event of Default under this Agreement (each an "EVENT OF DEFAULT"):

             (a) the occurrence of an Event of Default under the Note;

             (b) the Debtor otherwise fails to perform or breaches any material
obligation under this Agreement;

             (c) any material representation or warranty made herein by the
Debtor is untrue;

             (d) there occurs a material adverse change to the value of the
Collateral as determined by Secured Party in its reasonable discretion; or

             (e) the Debtor fails to maintain its corporate existence in good
standing.

         11. REMEDIES. Upon the occurrence of an Event of Default, Secured Party
shall be entitled to take one or more of the following actions:

             (a) all Obligations shall become due and payable as provided in the
Note;

             (b) the Secured Party shall have all the rights and remedies of a
secured party upon default, including but not limited to those provided under
the Uniform Commercial Code as in effect in the Commonwealth of Massachusetts or
any applicable jurisdiction;

             (c) the Debtor shall, upon the Secured Party's request, assemble
the Collateral and make it available to the Secured Party at a place to be named
by the Secured Party which is reasonably convenient to both parties;

             (d) the Secured Party shall have the right, without notice or legal
process but without a breach of the peace, to enter any place where the
Collateral is located for the purpose of taking possession and removing it;

             (e) unless the Collateral is perishable or threatens to decline
speedily in value or is of a type customarily sold on a recognized market, the
Secured Party shall give to the Debtor at least ten (10) days prior written
notice of the time and place of any public sale of Collateral or of the time
after which any private sale or any other intended disposition is to be made.
The Debtor hereby acknowledges that ten (10) days' prior written notice of such
sale or sales shall be reasonable notice. In addition, the Debtor waives any and
all rights that it may have to a judicial hearing in advance of the enforcement
of any of the Secured Party's rights and remedies hereunder, including, without
limitation, its right following an Event of Default to take immediate possession
of the Collateral and to exercise its rights and remedies with respect thereto;
and

                                       8
<PAGE>

             (f) Secured Party may declare the entire right, title, and interest
of the Debtor in any of the Intellectual Property that constitutes Collateral
vested in the Secured Party, in which event such right, title, and interest
shall immediately vest in the Secured Party and in which case the Secured Party
shall be entitled to exercise the power of attorney referred to in Section 14
hereof to execute, cause to be acknowledged and notarized and to record said
absolute assignment with the applicable agency;

             (g) take and practice or sell any of the Intellectual Property that
constitutes Collateral;

             (h) direct the Debtor to refrain, in which event the Debtor shall
refrain, from practicing any of the Intellectual Property that constitutes
Collateral directly or indirectly, and the Debtor shall execute such other and
further documents as the Secured Party may request further to confirm this and
to transfer ownership of the Collateral to the Secured Party;

             (i) the Debtor shall, in connection with any disposition of
Collateral, execute and deliver to the Secured Party an Assignment of Patents
and Patent Applications substantially in the form attached as Exhibit A hereto.
If the Debtor fails to provide such document within (10) ten days after it has
been requested by the Secured Party, then the Secured Party may complete such
document by exercise of a power of attorney hereby granted by the Debtor. Such
power of attorney is coupled with an interest and is irrevocable; and

             (j) the Debtor shall remain liable for any deficiency remaining
after any sale. The Secured Party's reasonable attorney's fees shall be included
in the costs of sales preparation.

         12. [Intentionally omitted]

         13. SECURED PARTY'S OBLIGATIONS AND DUTIES.

             Anything herein to the contrary notwithstanding, the Debtor shall
remain obligated and liable under each contract or agreement comprised in the
Collateral to be observed or performed by the Debtor thereunder. The Secured
Party shall not have any obligation or liability under any such contract or
agreement by reason of or arising out of this Agreement or the receipt by the
Secured Party of any payment relating to any of the Collateral, nor shall the
Secured Party be obligated in any manner to perform any of the obligations of
the Debtor under or pursuant to any such contract or agreement, to make inquiry
as to the nature or sufficiency of any payment received by the Secured Party in
respect of the Collateral or as to the sufficiency of any performance by any
party under any such contract or agreement, to present or file any claim, to
take any action to enforce any performance or to collect the payment of any
amounts which may have been assigned to the Secured Party or to which the
Secured Party may be entitled at any time or times. The Secured Party's sole
duty with respect to the custody, safe keeping and physical preservation of the
Collateral in its possession, under the UCC or otherwise, shall be to deal with
such Collateral in the same manner as the Secured Party deals with similar
property for its own account.

                                       9
<PAGE>

         14. POWER OF ATTORNEY.

             (a) The Debtor hereby irrevocably constitutes and appoints the
Secured Party and any officer or agent thereof, with full power of substitution,
as its true and lawful attorneys-in-fact with full irrevocable power and
authority in the place and stead of the Debtor or in the Secured Party's own
name, for the purpose of carrying out the terms of this Agreement, to take any
and all appropriate action and to execute any and all documents and instruments
that may be necessary or useful to accomplish the purposes of this Agreement
and, without limiting the generality of the foregoing, hereby gives said
attorneys the power and right, on behalf of the Debtor, without notice to or
assent by the Debtor, to do the following upon the occurrence of an Event of
Default, generally to sell, transfer, pledge, make any agreement with respect to
or otherwise dispose of or deal with any of the Collateral in such manner as is
consistent with the UCC and as fully and completely as though the Secured Party
were the absolute owner thereof for all purposes, and to do, at the Debtor's
expense, at any time, or from time to time, all acts and things which the
Secured Party deems necessary or useful to protect, preserve or realize upon the
Collateral and the Secured Party's security interest therein, in order to effect
the intent of this Agreement, all no less fully and effectively as the Debtor
might do, including, without limitation, (i) the filing and prosecuting of
registration and transfer applications with the appropriate federal, state or
local agencies or authorities with respect to trademarks, copyrights and
patentable inventions and processes, (ii) upon written notice to the Debtor, the
exercise of voting rights with respect to voting securities, which rights may be
exercised, if the Secured Party so elects, with a view to causing the
liquidation of assets of the issuer of any such securities and (iii) the
execution, delivery and recording, in connection with any sale or other
disposition of any Collateral, of the endorsements, assignments or other
instruments of conveyance or transfer with respect to such Collateral.

             (b) To the extent permitted by law, the Debtor hereby ratifies all
that said attorneys shall lawfully do or cause to be done by virtue hereof. This
power of attorney is a power coupled with an interest and is irrevocable. The
powers conferred on the Secured Party hereunder are solely to protect its
interests in the Collateral and shall not impose any duty upon it to exercise
any such powers. The Secured Party shall be accountable only for the amounts
that it actually receives as a result of the exercise of such powers, and
neither it nor any of its officers, directors, employees or agents shall be
responsible to the Debtor for any act or failure to act, except for the Secured
Party's own gross negligence or willful misconduct.

         15. NO WAIVER BY SECURED PARTY, ETC. The Secured Party shall not be
deemed to have waived any of its rights and remedies in respect of the
Obligations or the Collateral unless such waiver shall be in writing and signed
by the Secured Party. No delay or omission on the part of the Secured Party in
exercising any right or remedy shall operate as a waiver of such right or remedy
or any other right or remedy. A waiver on any one occasion shall not be
construed as a bar to or waiver of any right or remedy on any future occasion.
All rights and remedies of the Secured Party with respect to the Obligations or
the Collateral, whether evidenced hereby or by any other instrument or papers,
shall be cumulative and may be exercised singularly, alternatively, successively
or concurrently at such time or at such times as the Secured Party deems
expedient.

         16. SURETYSHIP WAIVERS BY DEBTOR. The Debtor waives demand, notice,
protest, notice of acceptance of this Agreement, notice of loans made, credit
extended, Collateral received or delivered or other action taken in reliance
hereon and all other demands and notices

                                       10
<PAGE>

of any description. With respect to both the Obligations and the Collateral, the
Debtor assents to any extension or postponement of the time of payment or any
other indulgence, to any substitution, exchange or release of or failure to
perfect any security interest in any Collateral, to the addition or release of
any party or person primarily or secondarily liable, to the acceptance of
partial payment thereon and the settlement, compromising or adjusting of any
thereof, all in such manner and at such time or times as the Secured Party may
deem advisable. Except as required by applicable law, the Secured Party shall
have no duty as to the collection or protection of the Collateral or any income
therefrom, the preservation of rights against prior parties, or the preservation
of any rights pertaining thereto beyond the safe custody thereof as set forth in
Section 13 above. The Debtor further waives any and all other suretyship
defenses.

         17. MARSHALLING. The Secured Party shall not be required to marshal any
present or future collateral security (including but not limited to the
Collateral) for, or other assurances of payment of, the Obligations or any of
them or to resort to such collateral security or other assurances of payment in
any particular order, and all of its rights and remedies hereunder and in
respect of such collateral security and other assurances of payment shall be
cumulative and in addition to all other rights and remedies, however existing or
arising. To the extent that it lawfully may, the Debtor hereby agrees that it
will not invoke any law relating to the marshalling of collateral which might
cause delay in or impede the enforcement of the Secured Party's rights and
remedies under this Agreement or under any other instrument creating or
evidencing any of the Obligations or under which any of the Obligations is
outstanding or by which any of the Obligations is secured or payment thereof is
otherwise assured, and, to the extent that it lawfully may, the Debtor hereby
irrevocably waives the benefits of all such laws.

         18. PROCEEDS OF DISPOSITIONS; EXPENSES. The Debtor shall pay to the
Secured Party on demand any and all expenses, including reasonable attorneys'
fees and disbursements, incurred or paid by the Secured Party in protecting,
preserving or enforcing the Secured Party's rights and remedies under or in
respect of any of the Obligations or any of the Collateral. After deducting all
of said expenses, the residue of any proceeds of collection or sale or other
disposition of Collateral shall, to the extent actually received in cash, be
applied to the payment of the Obligations in such order or preference as the
Secured Party may determine, proper allowance and provision being made for any
Obligations not then due. Upon the final payment and satisfaction in full of all
of the Obligations and after making any payments required by Sections
9-608(a)(1)(c) or 9-615(a)(3) of the UCC, any excess shall be returned to the
Debtor. In the absence of final payment and satisfaction in full of all of the
Obligations, the Debtor shall remain liable for any deficiency.

         19. GENERAL. The following general provisions apply:

             (a) except to the extent specifically referenced, this Agreement,
together with the Note and the Collaboration Agreement are the only agreements
between the parties regarding its subject matter. They supersede all prior or
contemporaneous agreements, whether oral or written;

             (b) no modification or waiver of this Agreement shall be effective
unless contained in a writing signed by the modifying or waiving party. The
waiver of any default shall not be deemed a waiver of any other or subsequent
default;

                                       11
<PAGE>

             (c) all remedies shall be cumulative;

             (d) section headings and other titles are for convenience only and
shall not be used in construing or interpreting this Agreement. Any provision of
this Agreement which is unenforceable shall be severed and the remainder of this
Agreement enforced to the fullest extent permitted by law. This Agreement shall
be governed by and construed under the laws of the Commonwealth of
Massachusetts, including its choice of law rules; and

             (e) this Agreement shall be binding on the parties and their
respective successors and assigns.

         20. NOTICES. Except in the case of notices and other communications
expressly permitted to be given by telephone, all notices and other
communications provided for herein shall be in writing and shall be delivered by
hand or overnight courier service, mailed by certified or registered mail or
sent by telecopy, as follows:

             (a) if to the Secured Party, to Genzyme Corporation, One Kendall
Square, Cambridge, Massachusetts 02139-1562, Attn: Mr. Michael Wyzga, Telephone:
(617) 252-7500, Facsimile: (617) 252-7802; with a copy to: Genzyme Corporation,
One Kendall 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 Technology Square,
Cambridge, Massachusetts 02139, Attention: President, Telephone: (617) 225-2500,
Facsimile: (617) 225-2501), with a copy to: Dyax Corp., 300 Technology Square,
Cambridge, Massachusetts 02139, Attention: Vice President, Legal Affairs,
Telephone: (617) 225-2500, Facsimile: (617) 225-2501).

         IN WITNESS WHEREOF, the parties have executed this Agreement under seal
as of the date first above written.

GENZYME CORPORATION                        DYAX CORP.

By: /s/ G. Jan Van Heek                    By: /s/ Jack Morgan
   --------------------------------            ---------------------------------
   Name:  G. Jan Van Heek                      Name:  Jack Morgan
   Title: Executive Vice President             Title: Senior Vice President

                                       12
<PAGE>

                                   SCHEDULE A

                               DYAX PATENT RIGHTS

<TABLE>
<CAPTION>

--------------------------------------------------------------------------------------------------------------------------
                                           APPLICATION
           COUNTRY                            NUMBER                   FILING DATE                     STATUS
--------------------------------------------------------------------------------------------------------------------------
<S>                                    <C>                              <C>               <C>
      U.S. (Markland 1)                     08/179,964                    1/11/94              Abandoned in favor of US
                                                                                                      08/208,264

--------------------------------------------------------------------------------------------------------------------------

   U.S. CIP (Markland 1A)                   08/208,264                    3/10/94               U.S. Patent 6,057,287

                                                                                                   issued 5/02/00

--------------------------------------------------------------------------------------------------------------------------

 U.S. CIP (Markland 1A Div)                 09/421,097                   10/19/99               U.S. Patent 6,333,402

                                                                                                   issued 12/25/01
--------------------------------------------------------------------------------------------------------------------------

   U.S. CIP (Markland 1B)                   08/676,125                    9/25/96               U.S. Patent 5,795,865

                                                                                                   issued 8/18/98

--------------------------------------------------------------------------------------------------------------------------

 U.S. Div. (Markland 1B Div)                09/136,012                    8/17/98               U.S. Patent 5,994,125

                                                                                                   issued 11/30/99

--------------------------------------------------------------------------------------------------------------------------

    Canada (Markland 1B)                    2,180,950                     1/11/95                      Pending

--------------------------------------------------------------------------------------------------------------------------

      EPO (Markland 1B)                    95/909223.0                    1/11/95                      Pending

                                       pub 0739355 10/30/96

--------------------------------------------------------------------------------------------------------------------------

     Japan (Markland 1B)                     7-518726                     1/11/95                     Published

--------------------------------------------------------------------------------------------------------------------------

      PCT (Markland 1B)                      US95/00299                   1/11/95

                                             WO95/21601

--------------------------------------------------------------------------------------------------------------------------
</TABLE>

                                       13
<PAGE>

                                   SCHEDULE B

EXISTING INDEBTEDNESS:

CAPITAL LEASE OBLIGATIONS

Master Lease Agreement between General Electric Capital Corporation and Dyax
Corp. (indebtedness under lease line as of March 31, 2002 of $4,846,221 with
commitment to extend additional line of $5,000,000)

Master Lease Agreement between Transamerica Business Credit Corporation and Dyax
Corp. (indebtedness under lease line of March 31, 2002 of $1,417,844)

Master Lease Agreement between Dyax SA and Locabel (current indebtedness of Euro
553,295,14 with ability to extend to Euro 1,250,000)

OTHER DEBT

Loan obligation of Massachusetts Institute of Technology to Dyax Corp. under
Lease Agreement to loan up to $35 per rentable square foot to fund portion of
Tenant's Work (total debt not to exceed $2,400,000)

Virginia National Bank as holder of promissory note in amount of $4,250,000
given by Biotage Real Estate LLC to Industrial Development Authority of
Albemarle County, Virginia to fund land acquisition and construction of new
facility for Biotage, Inc.

EXISTING LIENS:

Letter of Credit for benefit of Massachusetts Institute of Technology
($4,279,932) to secure obligations under Lease Agreement for 300 Technology
Square

All Equipment acquired pursuant to Master Lease Agreements under 3 Existing
Capital Lease Obligations listed above

Real Estate located in Albemarle County, Virginia to secure obligations under
Promissory Note held by Virginia National Bank

                                       14
<PAGE>

                                    EXHIBIT A

                  ASSIGNMENT OF PATENTS AND PATENT APPLICATIONS

         In consideration of good and valuable consideration, the sufficiency
and receipt of which are hereby acknowledged, _______________________(the
"Company"), a corporation organized under the laws of the state of
________________, having an office at ____________________________________,
hereby sells, assigns, transfers and sets over unto
_______________________________________________a corporation organized under the
laws of the State of __________, having an office at __________________________,
(the "Assignee"), the entire right, title, and interest in and to the Patents
and Patent Applications listed on Schedule A attached hereto, in and for the
United States, the same to be held and enjoyed by said Assignee, its successors,
assigns, or other legal representatives, to the full ends of the terms for
which all Patents therefor may be granted, as fully and entirely as the same
would have been held and enjoyed by the Company if this assignment had not been
made.

         And by this covenant the Company will execute or procure any further
necessary assurance of title to said Patents and Patent Applications in said
Assignee, its successors, assigns or other legal representatives, and, upon the
request of said Assignee, will make all rightful oaths and do all lawful acts
requisite for procuring the same or for aiding therein, without further
compensation, its successors, assigns, or other legal representatives.

         And the Commissioner of Patents and Trademarks is hereby authorized and
requested to issue any and all Patents, and Patents emanating from the Patent
Applications, to said Assignee.

                                               DYAX CORP.

                                               By:
                                                   ----------------------------

                                               Name:

                                               Title:

State of _______________   )

                           )  ss

County of _____________    )

                                       15
<PAGE>

         Before me this ___ day of _______ 20__, personally appeared
_______________________ to me personally known to be the person described in and
who executed the above instrument, and acknowledged to me that he executed the
same of his own free will for the purposes therein set forth.

                                                      ------------------------

                                                      Notary Public

AFFIX SEAL

                                       16

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