Document:

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                                                                Exhibit 10.12

                                    SUBLEASE

      This instrument is a Sublease (the "Sublease") dated as of January __,
1999 between MITOTIX, INC., a Delaware corporation ("Sublessor"), and DYAX
CORP., a Delaware corporation ("Sublessee").

      The parties to this instrument hereby agree with each other as follows:

                                    Article I

                      SUMMARY OF BASIC SUBLEASE PROVISIONS

      1.1 BASIC DATA

ALL CAPITALIZED TERMS USED HEREIN SHALL HAVE THE MEANINGS ASCRIBED TO THEM IN
THE PRIME LEASE (hereinafter defined) UNLESS OTHERWISE DEFINED HEREIN.

Commencement Date:                       February 1, 1999

Sublessor:                               Mitotix, Inc.

Present Mailing Address of Sublessor:    One Kendall Square, Building 600
                                         Cambridge, Massachusetts 02139

Sublessee:                               Dyax Corp.

Present Mailing Address of Sublessee:    One Kendall Square, Building 600
                                         Cambridge, Massachusetts  02139

Permitted Uses:                          General office research and
                                         development, laboratories, light
                                         manufacturing, marketing, storage and
                                         sale of biologically derived products
                                         in connection with biological and
                                         chemical research.

Premises:                                Approximately 7,620 rentable square
                                         feet of space located on the second
                                         floor of the building known as
                                         Building 600-650-700 (the "Building")
                                         located at One Kendall Square,
                                         Cambridge, Massachusetts as
                                         approximately shown on the attached
                                         Exhibit A.  The Premises demised under
                                         this Sublease comprise a portion of
                                         the premises leased (the "Leased
                                         Premises") to Sublessor by Prime
                                         Lessor (as defined below) under the
                                         Prime Lease (as defined below).
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Prime Lease:                             That certain lease, dated as of
                                         November 5, 1992, between the Trustees
                                         of Old Kendall Trust (the "Initial
                                         Prime Landlord"), as lessor, and
                                         Sublessor, as lessee, as amended to
                                         date.

Prime Lessor:                            Cambridge Athenaeum LLC, as successor
                                         to the Initial Prime Landlord.

Base Rent (based on 7,620 rentable       $304,800.00 per annum ($40.00 per
square fee)                              rentable square feet), payable in
                                         monthly installments of $25,400.00
                                         each.

Additional Rent:                         So that the Base Rent payable to
                                         Sublessor hereunder shall be net to
                                         Sublessor (except for the exclusions
                                         described below), Sublessee shall pay
                                         as additional rent hereunder: (a)
                                         Sublessee's Share of all amounts in
                                         the nature of pass throughs of
                                         operating expenses, insurance charges
                                         and charges for utility usage payable
                                         by Sublessor as tenant under the Prime
                                         Lease to the Prime Lessor in
                                         connection with operating expenses,
                                         insurance charges and utility charges
                                         attributable generally to the Building
                                         or the Leased Premises under the Prime
                                         Lease, including the Premises,
                                         specifically including, without
                                         limitation, all amounts paid by
                                         Sublessor to Prime Lessor as "Rent
                                         Adjustments" under Sections 5.1 - 5.4
                                         of the Prime Lease (in that regard,
                                         Sublessor shall deliver to Sublessee a
                                         copy of the annual statement of
                                         operating expenses received by
                                         Sublessor from Prime Lessor under
                                         Section 5.3 of the Prime Lease and a
                                         copy of the tax bills and statement of
                                         taxes received by Sublessor from Prime
                                         Lessor under Section 5.4 of the Prime
                                         Lease); (b) Sublessee's Share of all
                                         charges and costs attributable to the
                                         Leased Premises under the Prime Lease
                                         which are also allocable to the
                                         Premises hereunder (including, without
                                         limitation dumpster charges and
                                         costs), (c) any expenses, taxes,
                                         insurance charges, and utility charges
                                         that are (i) incurred by Sublessor in
                                         connection with its providing of those
                                         utilities, maintenance and repair
                                         services required to be provided by
                                         Sublessor under the terms of this
                                         Sublease and (ii) applicable
                                         exclusively to the Premises; (d) any
                                         additional

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                                         costs incurred by Sublessor in
                                         connection with its provision of those
                                         utilities, maintenance and repairs
                                         which Sublessor is required under the
                                         terms of this Sublease to provide to
                                         the Premises. Such Additional Rent
                                         shall exclude however, the following:
                                         (a) costs attributable solely to those
                                         portions of the Leased Premises
                                         retained by Sublessor and not to the
                                         Premises demised hereunder; (b) costs
                                         payable by Sublessor as tenant under
                                         the Prime Lease in the nature of late
                                         penalties or interest, damages payable
                                         on account of tenant defaults,
                                         accelerated rents or charges except to
                                         the extent any such costs are incurred
                                         in connection with a default by
                                         Sublessee under this Sublease; (c) any
                                         costs for utilities or the like that
                                         are separately metered to the Premises
                                         and that Sublessee pays directly to the
                                         utility company or service provider;
                                         and (d) costs payable by Sublessor for
                                         Sublessor's parking spaces in the Old
                                         Kendall Square Garage in accordance
                                         with Section 4(ii) of the Prime Lease.

Security Deposit:                        None.

Sublessee's Share:                       The rentable square footage of
                                         Premises divided by the rentable
                                         square footage of the Leased Premises,
                                         expressed as a percentage; as of the
                                         date of this Sublease, based upon the
                                         Premises containing 7,620 rentable
                                         square feet, Sublessee's Share shall
                                         be 24.32%

Sublessee's Term or Term:                Beginning on the Commencement Date and
                                         expiring at midnight on June 30, 2000,
                                         unless extended as provided herein.

Sublessee's Term Extension Rights:       Notwithstanding any provision in this
                                         Sublease to the contrary, Sublessee
                                         shall have the following term
                                         extension rights with respect to the
                                         Term of the Sublease; Sublessee may
                                         exercise such rights by giving
                                         Sublessor written notice on or prior
                                         to January 1, 2000, of Sublessee's
                                         election of one of the following: (a)
                                         to confirm that Sublessee intends to
                                         vacate the Premises by June 30, 2000;
                                         or (b) provided

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                                         that Sublessee is not in default under
                                         this Sublease beyond any applicable
                                         notice, grace or cure period, to extend
                                         the Term of the Sublease through
                                         midnight on December 31, 2000, subject,
                                         however to Sublessor's Recapture Rights
                                         (as defined below), but otherwise on
                                         all of the terms and conditions of this
                                         Sublease.

Sublessor's Recapture Rights:            If Sublessee exercises its right to
                                         extend the Term through December 31,
                                         2000, Sublessor may, by giving
                                         Sublessee not less than six (6) months'
                                         prior written notice, "recapture" the
                                         portion of the Premises identified on
                                         Exhibit A as the "Recapture Space".
                                         Sublessor hereby agrees that it shall
                                         exercise its recapture rights hereunder
                                         if, and only if, Sublessor reasonably
                                         and in good faith determines, at such
                                         time as Sublessor gives Sublessee
                                         notice of Sublessor's exercise of its
                                         recapture rights, that Sublessor has a
                                         need for, and intends to occupy and
                                         use, the Recapture Space for the
                                         conduct therein by Sublessor of its
                                         business. Upon Sublessor's exercise of
                                         its Recapture Rights hereunder, the
                                         Sublease shall be deemed terminated
                                         with respect to the Recapture Space on
                                         the effective date specified in
                                         Sublessor's recapture notice, and Base
                                         Rent and other charges and Sublessee's
                                         Share hereunder shall be equitably
                                         adjusted to reflect the reduction of
                                         Sublessee's usable square footage.

Broker:                                  Fallon Hines & O'Connor, Inc. and Lynch
                                         Murphy Walsh and Partners, Incorporated

Sublessee's Parking Rights:              None.

                                   Article II

                                    PREMISES

      2.1 SUBLEASE OF PREMISES

Subject to and provided that Prime Lessor gives Prime Lessor's written consent
to the subleasing contemplated by the Sublease, Sublessor hereby subleases to
Sublessee, and Sublessee hereby

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accepts and subleases from Sublessor, upon and subject to the terms and
provisions of the Prime Lease, as both are defined in Section 1.1. Included as
part of the Premises sublet hereunder are all of Sublessor's appurtenant rights
under the Lease to use the common areas and facilities of the building and the
Lot (as defined in the Prime Lease), subject in all events to the Prime Lessor's
rights reserved and excepted in Section 2 of the Prime Lease.

      2.2 PRIME LEASE

            2.2.1 Sublessor hereby represents and warrants that : (i) Sublessor
is the tenant under the Prime Lease and has the full right to enter into this
Sublease (subject, however, to Prime Lessor' s consent); (ii) the Prime Lease is
in full force and effect; (iii) Sublessor has not received from Prime Lessor any
notice of any default on the part of Sublessor as tenant under the Prime Lease
which has not been cured, nor has Sublessor given Prime Lessor notice of any
default on the part of Prime Lessor as landlord under the Prime Lease which has
not been cured; (iv) Sublessor has submitted to Sublessee a true and complete
copy of those portions of the Prime Lease that are pertinent to or affect
Sublessee's rights and obligations under the Sublease; and (v) to the best of
Sublessor's knowledge and belief, the Premises and their electrical, mechanical,
plumbing, heating, ventilating and air-conditioning systems are in working order
and repair and in a condition adequate for the conduct in the Premises of
Sublessee's business. Sublessee warrants and acknowledges that it has reviewed
the Prime Lease and is satisfied with the arrangements therein reflected.
Sublessee also warrants that it is satisfied with the present condition of the
Premises (which Sublessee takes "as is" without any representation or warranty
by Sublessor regarding the condition of the Premises [except as set forth in
clause 2.2.1(v) above] or the fitness of the Premises for any particular use and
without any obligation of any kind on Sublessor to make any repairs or
improvements thereto in connection with Sublessee's occupancy) and with
Sublessee's ability to use the Premises on the terms herein set forth.

            2.2.2 The Prime Lease is by this reference incorporated into and
made a part hereof, except that

                  (i) all references in the Prime Lease to "Landlord", "Tenant",
            "Lease" and "Premises", respectively, shall be deemed to refer to
            Sublessor, Sublessee, this Sublease and the Premises subleased
            hereunder, respectively, except that all references in the following
            sections and/or provisions of the Prime Lease to "Landlord",
            "Tenant", "Lease", and "Premises", respectively, shall be deemed to
            refer to "Prime Lessor", "Sublessee", this "Sublease" and the
            "Premises subleased hereunder", respectively (i.e., it is the
            intention of the parties that Prime Lessor shall retain all of its
            rights and obligations under such sections and/or provisions; that
            Sublessor shall not be entitled to exercise any of Prime Lessor's
            rights, nor shall be bound by any of Prime Lessor's obligations,
            under such sections and/or provisions, and that Sublessee shall be
            entitled to exercise all of Tenant's rights, and shall be bound by
            all of Tenant's obligations, under such sections and/or provisions):

                  (a) All of Section 2, except for the first sentence, relating
            to appurtenant rights and Prime Lessor's reserved rights.

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                  (b) Section 6 (Utilities and Other Services), except that to
            the extent utilities are not separately metered for the Premises,
            Sublessee shall make payments on account of utilities to Sublessor
            as Additional Rent under this Sublease and not to Prime Lessor.

                  (c) The first grammatical paragraph of Section 9A (Insurance -
            Waiver of Subrogation), except that the comprehensive general
            liability insurance that Sublessee must procure thereunder shall
            also name Sublessor as an additional insured and the indemnity
            provided in such Section shall inure to the benefit of Sublessor.

                  (d) Section 10 (Maintenance of Leased Premises), except that
            Sublessee shall be deemed to be obligated to maintain and operate
            the Premises in the condition required thereunder not only for the
            benefit of Prime Lessor, but also for the benefit of Sublessor, who
            shall be entitled to enforce Sublessee's maintenance obligations and
            other covenants thereunder.

                  (e) Section 13 (Subordination)

                  (f) Sections 17.1 - 17.3 (Fire, Casualty)

                  (g) Section 17A (Eminent Domain)

                  (h) Section 19 (Rules and Regulations)

                  (ii) the following sections and/or provisions of the Prime
            Lease are expressly excluded from this Sublease (i.e., they shall be
            deemed to be incorporated in this Sublease) either because they are
            inapplicable or because they are superseded by specific provisions
            hereof:

                  (a) Section 1 (Parties)

                  (b) The first sentence of Section 2 (Leased Premises),
            relating to the description of the Premises, and the last
            grammatical paragraph of Section 2, relating to parking rights in
            the Kendall Square Garage.

                  (c) Section 3.1 (Term)

                  (d) Section 4 (Rent)

                  (e) Sections 5.1 through 5.4.4 (Rent Adjustments), except that
            these provisions shall be included for the limited purpose of
            determining the amount of Additional Rent payable by Sublessee on
            account of Rent Adjustments payable by Sublessor under the Prime
            Lease.

                  (f) Section 12 (Assignment - Subletting)

                  (g) Section 17.4 (Abatement of Rent)

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                  (h) Section 20 (Broker

                  (i) Section 22 (Notice)

                  (j) Section 24 (Option to Extend)

                  (k) Section 25 (Right of Second Opportunity)

            2.2.3 This Sublease is and shall remain subject and subordinate in
all respects to the Prime Lease and to all renewals, modifications,
consolidations, replacements and extensions thereof. This Section 2.2.3 shall be
self-operative and no further instrument of subordination shall be required. In
the event of termination or cancellation of the Prime Lease for any reason
whatsoever with respect to all or any portion of the Premises, this Sublease
shall automatically terminate with respect to all or such portion of the
Premises.

            2.2.4 Notwithstanding anything contained in this Sublease to the
contrary, Sublessor shall have no obligation during the term of this Sublease to
provide any services of any nature whatsoever to Sublessee or to, in or for the
benefit of the Premises or to expend any money for the preservation or repair of
the Premises, or to observe or perform any obligations of Sublessor under this
Sublease in any case where such services, expenditures or obligations are
required under the Prime Lease to be provided, performed or observed by Prime
Lessor for the benefit of Sublessor with respect to the Premises, and Sublessee
agrees to look solely and directly to Prime Lessor for the furnishing of any
such services, expenditure of any such sums, or observance or performance of any
such obligations to which, or the benefit of which, Sublessee may be entitled
under this Sublease, but nothing in the foregoing shall be deemed to exculpate
or otherwise release Sublessor from, or prevent Sublessee from looking directly
to Sublessor for, any liability arising out of Sublessor's negligence or the
failure of Sublessor to perform its express obligations hereunder; nor shall the
foregoing relieve Sublessor of its express obligations set forth in this
Sublease. Sublessor shall, however, upon the request of Sublessee from time to
time (which request may be oral), use due diligence and reasonable efforts to
cause Prime Lessor to furnish such services, expend such sums, and observe and
perform such obligations. Sublessor's only obligations under the Prime Lease
with respect to the Premises are to use the aforesaid due diligence and
reasonable efforts, make those payments of all rent and other charges due to
Prime Lessor thereunder and to make those payments due to the utility providers
for utility services (including electricity, water and sewer) which are
separately metered to the Leased Premises, which payments Sublessor hereby
agrees to make, provided, however, that Sublessee makes timely payment to
Sublessor of all rent and other charges payable under this Sublease. Sublessor
hereby agrees that, so long as Sublessee makes timely payment to Sublessor of
all rent and other charges payable by Sublessee hereunder, Sublessor shall make
timely payment of all rent and other charges due to Prime Lessor as landlord
under the Sublease. It is the intention of the parties that Sublessee comply
with all of Sublessor's obligations as tenant under the Prime Lease (not
excluded under Section 2.2.2 above) with respect to the Premises to the same
extent and with the same force and effect as if Sublessee were tenant
thereunder, and Sublessee hereby agrees to so comply with all of Sublessor's
such obligations under the Prime Lease with respect td the Premises. Sublessee
shall have no claim against Sublessor for any default by the Prime Lessor under
Prime Lease. If as a result of any default by Prime Lessor as landlord under the
Prime Lease, Sublessor as tenant under the Prime Lease is entitled to any

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offset or similar rights against Prime Lessor, Sublessee shall be entitled to a
fair and equitable share of such offset or similar rights. So long as Sublessee
is not in default under this Sublease beyond any applicable notice, grace or
cure period, Sublessee shall have the right, subject to the prior written
consent of Sublessor, which consent shall not be unreasonably withheld and shall
be given or withheld by Sublessor five (5) business days after receipt of the
request therefor, to maintain, in the name of Sublessor but at Sublessee's sole
cost and expense, an action or actions to compel Prime Lessor to discharge the
responsibilities of Prime Lessor under the Prime Lease. Sublessor shall not
unreasonably withhold its consent to the bringing of any such action or actions
by Sublessee, provided, in each instance, that Sublessee shall not sue if
Sublessor has itself commenced an action or actions for the same purpose; and
provided, further, that Sublessor may withhold its consent if, in Sublessor's
judgment, such action would result in an increase in rent, additional rent, or
any other sums whatsoever payable by Sublessor to Prime Lessor under the Prime
Lease. In any event, Sublessee agrees to indemnify Sublessor and hold Sublessor
harmless from and against all loss, cost, damage, expense, or liability
(including, without limitation, attorney's fees and disbursements) which
Sublessor may incur by reason of any action brought by Sublessee against Prime
Lessor. No default by Prime Lessor under the Prime Lease shall excuse Sublessee
from the performance of any of its obligations to be performed under this
Sublease or to any reduction in or abatement of any of the rent provided for in
this Sublease, unless and only to the extent that Sublessor shall be excused
from the performance of a corresponding obligation as the "tenant" under the
Prime Lease.

            2.2.5 Sublessee shall neither do, nor permit to do nor permit to be
done, anything that would increase Sublessor's obligations to the Prime Lessor
under the Prime Lease (unless Sublessee shall indemnify Sublessor from such
increased obligation) or that would cause the Prime Lease to be terminated or
forfeited. Sublessor shall not amend or modify (nor agree to amend or modify)
the Prime Lease in any way that would increase Sublessee's obligations or
diminish Sublessee's rights under this Lease, nor shall Sublessor do, nor permit
to do or be done, anything that would cause the Prime Lease to be cancelled,
terminated or forfeited.

            2.2.6 Sublessor shall promptly give Sublessee a copy of any notice
of default, termination or otherwise affecting the existence or validity of the
Sublease or relating to any casualty or taking, given by Sublessor or Prime
Lessor to the other.

                                   Article III

                                TERM OF SUBLEASE

      3.1 TERM

      The Sublease Term of this Sublease shall be for the period specified in
Section 1.1 as the Sublease Term, unless earlier terminated as provided herein.

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                                   Article IV

                              CONDITION OF PREMISES

      4.1 CONDITION OF PREMISES

      Sublessee acknowledges that it has accepted the Premises "as is", in the
order and condition as the Premises are in on the date hereof, and agrees that
Sublessor is under no Obligation to perform any work upon or alteration to the
Premises for Sublessee's use and occupancy.

      4.2 FIXTURES AND EQUIPMENT

      Sublessee shall be entitled to use all built-in fixtures and equipment
physically located in the Premises as of the Commencement Date. Such fixtures
and equipment shall include four fume hoods, one glass washer and two
autoclaves; Sublessor represents and warrants that, to its best knowledge and
belief, all such fixtures and equipment are in good working order and repair
(except for one autoclave that is not in good working order, as previously
disclosed to Sublessee). Sublessee shall, at its expense, maintain and repair
such fixtures and equipment in good order, repair and condition and shall
surrender all such fixtures and equipment to Sublessor in such condition at the
end of the term.

                                    Article V

                                       USE

      5.1 PERMITTED USE

      Sublessee agrees that the Premises shall be used and occupied for the
Permitted Uses specified in Section 1.1 only. During the Sublease Term,
Sublessee shall assume and maintain exclusive control of the Premises. Sublessee
acknowledges and understands that it shall be responsible, at its expense, for
providing any janitorial, cleaning, equipment and fixture maintenance and
security services necessary for Sublessee' s use and occupancy of the Premises.
Sublessee shall have access to the Premises and the appurtenant common areas of
the Building 24 hours per day, seven days per week, subject to such "after
hours" security systems, rules and regulations as Prime Lessor may from time to
time impose.

      5.2 ASSIGNMENT AND SUBLETTING

      Sublessee shall not, by operation of law or otherwise, assign, mortgage,
pledge, encumber or in any manner transfer this Sublease, or any part thereof or
any interest of Sublessee hereunder, or sublet or permit the Premises or any
part thereof to be used or occupied by others, without the prior consent of both
Sublessor and Prime Lessor. Sublessor agrees that it shall not unreasonably
withhold or delay its consent to any assignment or further sublease to which
Prime Lessor may consent. Notwithstanding any such consent, Sublessee shall
remain liable to Sublessor for the payment of all rent and for the performance
of the covenants and conditions of this Sublease (which liability, following any
assignment, shall be joint and several with the assignee).

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                                   Article VI

                                      RENT

            6.1 BASE RENT; ADDITIONAL RENT

            (a) The Base Rent and Additional Rent specified in Section 1.1
hereof (collectively, the "Rent"), and any additional rent or other charges
payable pursuant to this Sublease shall be payable by Sublessee to Sublessor at
Sublessor's mailing address (or such other place as Sublessor may from time to
time designate by notice to Sublessee).

            (b) Rent shall be payable, in advance, on or before the twenty-fifth
(25th) day of each and every calendar month during the term of this Sublease.
Sublessor shall promptly deliver to Sublessee (i) a copy of the year end
statement of operating expenses that Sublessor receives from Prime Lessor as
provided in Section 5.3 of the Prime Lease, and (ii) a copy of each tax bill
received by Sublessor from Prime Lessor as provided in Section 5.4.3 of the
Prime Lease. Promptly after Sublessor and Prime Lessor have made the appropriate
adjustments between themselves on account of such actual operating expenses and
real estate taxes, the amounts paid by Sublessee as Sublessee's Share of such
estimated installments shall be adjusted between Sublessor and Sublessee. The
parties obligations hereunder to make such adjustments shall survive the
expiration or termination of this Sublease.

            (c) Rent for any partial month shall be paid by Sublessee to
Sublessor at such rate on a prorata basis. Other charges payable by Sublessee on
a monthly basis, as hereinafter provided, shall likewise be prorated.

      All Rent and other amounts due under this Sublease shall be made without
demand, offset or deduction. Sublessee shall be entitled to a fair and equitable
share of all rent abatements set forth in the Prime Lease which Sublessor has
been granted with respect to the Premises.

      6.2 LATE PAYMENTS; ADDITIONAL RENT

      If any installment of Rents, additional rent or other charges is not paid
on or before the date such payment is due and payable, and if as a result
Sublessor is obligated to pay to Prime Lessor the late charge specified in
Section 1 6(A)(d) of the Prime Lease, then Sublessee shall pay to Sublessor a
late charge of five percent (5%) of the amount of such payment. In addition, if
Sublessee shall fail to make any such payment within thirty (30) days after the
due date, such payment shall bear interest at the rate per annum which is two
percent (2%) higher than the "prime rate" then being charged by The First
National Bank of Boston from the date such payment became due to the date of
payment thereof by Sublessee; provided, however, that nothing contained herein
shall be construed as permitting Sublessor to charge or receive interest in
excess of the maximum legal rate than allowed by law. Such late charge and
interest shall constitute additional rent due and payable hereunder with the
next installment of Base Rent due hereunder.

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      6.3 EXCESS UTILITY COSTS

      If Sublessor, in its reasonable judgment, determines that Sublessee is
using excessive quantities of HVAC, electricity or water (for purposes of this
Sublease, "excessive quantities" shall mean quantities more than 10% higher than
the quantities being consumed by Sublessor [calculated on a per square foot
basis] in those portions of the Leased Premises used by Sublessor for purposes
comparable to Sublessee's use of the Premises), then in addition to paying
Sublessee's Share of utilities, Sublessee shall also, upon receipt of a written
invoice therefor, reimburse Sublessor for the cost of any such excess.

                                   Article VII

                       ALTERATIONS, FIXTURES AND EQUIPMENT

      7.1 ALTERATIONS

      Sublessee may not make any alterations, installations, and improvements to
the Premises without first obtaining the prior consent of both Sublessor and
Prime Lessor. Sublessor shall not be responsible for the failure or refusal of
Prime Lessor to consent to such improvements. Sublessor hereby agrees that it
shall not unreasonably withhold its consent to any alterations, additions or
improvements approved by Prime Lessor. Any such approved alterations, additions
or improvements shall be done at Sublessee's sole expense in a good and
workmanlike manner and in compliance with all applicable laws and codes and the
applicable requirements of the Prime Lease.

                                  Article VIII

                                SUBLESSEE'S RISK

      8.1 SUBLESSEE'S RISK

      Sublessee agrees to use and occupy the Premises at Sublessee's own risk;
and to the fullest extent permitted by law, Sublessor shall have no
responsibility or liability for any loss of or damage to fixtures or other
personal property of Sublessee, or of those claiming by, through or under
Sublessee, including without limitation, any loss or damage from the breaking,
bursting, crossing, stopping or leaking of electric cables and wires, and water,
gas, sewer or steam pipes or like matters.

                                   Article IX

                         SUBLESSOR'S ACCESS TO PREMISES

      9.1 SUBLESSOR'S RIGHT OF ACCESS

      If Sublessee fails to make any necessary repairs to the Premises within a
reasonable time after notice thereof from Sublessor, Sublessor shall have the
right to enter the Premises at all reasonable hours for the purpose of making
such repairs.

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                                    Article X

                                    INSURANCE

      10.1 SUBLESSEE'S INSURANCE

      Sublessee shall carry and maintain, throughout the term hereof, at its own
cost and expense, the insurance required under Section 9A of the Prime Lease;
such insurance shall name as additional insureds both Sublessor and Prime
Lessor.

                                   Article XI

                                    CASUALTY

      11.1 CASUALTY AND RESTORATION; EMINENT DOMAIN

      If the Premises, or any part thereof, shall be damaged or destroyed by
fire or other casualty or damage by eminent domain then Sublessee shall promptly
notify Prime Lessor and Sublessor. Under the Prime Lease the Prime Lessor is
obligated, as soon as possible thereafter, to repair or restore the Premises to
the extent and in the manner set forth in Sections 17 and 17A of the Prime
Lease, as the case may be. If Prime Lessor abates Sublessor's rent with respect
to the Premises as a result, then Rent and other charges hereunder shall be
similarly abated for so long as Sublessor is entitled to and receives an
abatement under the Prime Lease. If damage is of the type which entitles Prime
Lessor or Sublessor to terminate the Prime Lease and either such party so elects
to terminate the Prime Lease, then the Prime .Lease shall cease and come to an
end and this Sublease shall similarly terminate. In addition, if damage is of
the type which would entitle Sublessor to terminate the Prime Lease, Sublessee
shall have the right to exercise Sublessor's right of termination by giving both
Sublessor and Prime Lessor written notice of such termination within the
applicable notice period set forth in Sections 17 and 17A of the Prime Lease, as
the case may be. Sublessee acknowledges that Sublessor shall, in no event, have
any obligation whatsoever to rebuild or restore any damage to the Premises.

                                   Article XII

                            MISCELLANEOUS PROVISIONS

      12.1 WAIVER

      Failure on the part of either party to complain of any action or
non-action on the part of the other, no matter how long the same may continue,
shall never be deemed to be a waiver by such party of any of its rights
hereunder. Further, it is agreed that no waiver of any of the provisions hereof
by either party shall be construed as a waiver of any of the other provisions
hereof and that a waiver at any time of any of the provisions hereof shall not
be construed as a waiver at any subsequent time of the same provisions. The
consent to or approval of any action by, either party requiring such consent or
approval shall not be deemed to waive or render unnecessary such consent to or
approval of any subsequent similar act by such party.

                                       12
<PAGE>

      12.2 COVENANT OF QUIET ENJOYMENT

      Sublessee, subject to the terms and provisions of this Sublease, on
payment of the Rent and observing, keeping, and performing all of the terms and
provisions of this Sublease on Sublessee's part to be observed, kept, and
performed, shall lawfully, peaceably, and quietly have, hold, occupy, and enjoy
the Premises during the Sublease Term without hindrance or ejection by Sublessor
or by any person lawfully claiming under Sublessor, but subject to force
majeure; the foregoing covenant of quiet enjoyment is given in lieu of any other
covenant, whether express or implied.

      12.3 INVALIDITY OF PARTICULAR PROVISIONS

      If any term or provision of this Sublease, or the application thereof to
any person or circumstance, shall, to any extent, be invalid or unenforceable,
the remainder of this Sublease, or the application of such term or provision to
persons or circumstances other than those as to which it is held invalid or
unenforceable, shall not be affected thereby, and each term and provision of
this Sublease shall be valid and be enforced to the fullest extent permitted by
law.

      12.4 BROKERS

      Each party represents and warrants to the other that it has not directly
or indirectly dealt, with respect to the Premises and this Sublease with any
broker other than the Brokers identified in Section 1.1 (the "Brokers"). Each
party shall save harmless and indemnify the other party against any claims by
anyone with whom it has so dealt or by whom its attention was called to the
Premises, other than the Brokers, for a commission arising out of the execution
and delivery of this Sublease or out of negotiations between Sublessor and
Sublessee with respect to space in the Building. Sublessor agrees to pay the
Brokers the commission with respect to this Sublease set forth in a separate
agreement between Sublessor and the Brokers.

      12.5 PROVISIONS BINDING, ETC.

      Except as herein otherwise expressly provided, the terms hereof shall be
binding upon and shall inure to the benefit of the heirs, legal representatives,
successors and assigns, respectively, of Sublessor and Sublessee. Each term and
each provision of this Sublease to be performed by Sublessee shall be construed
to be both a covenant and a condition. The reference contained to the successors
and assigns of Sublessee is not intended to constitute a consent to assignment
by Sublessee, but has reference only to those instances in which Sublessor shall
have given its consent to a particular assignment if such consent is required by
the provisions of this Sublease. Each person executing this Sublease on behalf
of Sublessor warrants that Sublessor is a duly existing and valid Delaware
corporation qualified to do business in Massachusetts, that Sublessor has duly
executed and delivered this Sublease, that the execution and delivery of, and
the performance by Sublessor of its obligations under this Sublease are within
the powers of Sublessor and have been duly authorized by all requisite corporate
action, and that this Sublease is a valid and binding obligation of Sublessor in
accordance with its terms. Each of the persons executing this instrument on
behalf of the Sublessee hereby covenant and warrant that the Sublessee is a duly
existing and valid Delaware corporation qualified to do business in
Massachusetts, that Sublessee has duly executed and delivered this Sublease,
that the execution

                                       13
<PAGE>

and delivery of, and the performance by Sublessee of its obligations under this
Sublease are within the powers of Sublessee and have been duly authorized by all
requisite corporate action, and that the Sublease is a valid and binding
obligation of Sublessee in accordance with its terms.

      12.6 NO RECORDING

      Sublessee agrees not to record this Sublease or any notice thereof.

      12.7 NOTICES

      Whenever by the terms of this Sublease notice, demand or other
communication shall or may be given, either to Sublessor or to Sublessee, the
same shall be adequately given if in writing and delivered by hand or sent by
registered or certified mail, postage prepaid:

      If intended for Sublessor, addressed to it prior to the Commencement Date
      at the mailing address set forth in Section 1.1, with a courtesy copy to
      Sublessor's real estate attorneys Palmer & Dodge LLP, One Beacon Street,
      Boston, Massachusetts 02108, Attention: Thomas G. Schnorr, Esq. (or to
      such other address or addresses as may from time to time hereafter be
      designated by Sublessor by like notice).

      If intended for Sublessee, addressed to it the address set forth in
      Section 1.1, and after the Commencement Date addressed to it at the
      Premises to the attention of the Senior Vice President for Finance and
      Administration and Chief Financial Officer (to such other address or
      addresses as may from time to time hereafter be designated by Sublessee
      by, like notice).

All such notices shall be effective upon receipt or refusal to receive.

      12.8 PRIME LESSOR CONSENT

      This Sublease shall not be effective until and unless Prime Lessor has
given its consent hereto; Sublessor shall be responsible for paying all costs
and expenses payable to Prime Lessor under the Prime Lease in connection with
obtaining such consent. Sublessor shall not be responsible for the failure or
refusal of Prime Lessor to consent to this Sublease.

                                       14
<PAGE>

      EXECUTED UNDER SEAL, in any number of counterpart copies, each of which
counterpart copies shall be an original for all purposes, as of the day and year
first above written.

                             Sublessor: MITOTIX INC.

                                        By /s/ James Melanson
                                           ----------------------------------
                                          Its
                                          hereunto duly authorizes

                             Sublessee: DYAX CORP.

                                        By /s/ Keith S. Ehrlich
                                           ----------------------------------
                                          Its
                                          hereunto duly authorizes

                                       15<PAGE>

                                                                 Exhibit 10.13

                                COMMERCIAL LEASE

      THIS LEASE, made the 30th day of June 1999, by and between "Landlord",
Alan G. Dillard Jr., and "Tenant", Biotage a Div. of Dyax Corp.

                                   WITNESSETH:

      Landlord does hereby let and demise unto Tenant the hereinafter described
space in the building located on 1028 River Road Charlottesville, Virginia
22902.

                          DESCRIPTION OF DEMISED SPACE:

      Street Address: 1028 River Road, Charlottesville, VA 22902. Consisting of
8,200 square feet +/-.

                                 TERM OF LEASE:

      The term of this lease shall be from 1st day of September 1999 to the 31st
day of August 2001.

                            RENT AND ADDITIONAL RENT:

      The basic rent for the initial term:

            A.    First lease year, Fifty Eight Thousand Eight Hundred 00/100
            B.    Second lease year, Same

      The basic rent shall be payable each year in twelve equal monthly
installments, payable in advance on the first day of each calendar month.
September and October Rent due at Signing of Lease.

                                SECURITY DEPOSIT:

      Tenant agrees upon execution of this Lease Agreement by all parties that
Tenant will remit to Landlord a sum of Four Thousand Nine Hundred Dollars as a
security deposit. In the event of default by Tenant, Landlord may apply this
deposit toward any unpaid rent or related charges due from the Tenant. No
interest will be payable on the security deposit.

                             IMPROVEMENT BY TENANT:

      The Tenant shall have the right, from time to time, to make all such
alterations and improvements to, and decoration of, the interior of the leased
property as shall be reasonably necessary or appropriate for the conduct of
Tenant's business therein, provided that prior to the commencement of any such
alterations or improvements the Landlord shall in each case have approved them
in writing. If within thirty (30) days after such plans are submitted by the
Tenant to the Landlord for approval, Landlord shall not have given Tenant notice
of disapproval, stating the reasons for such disapproval, such plans and
specifications shall be considered approved by

                                                                               1
<PAGE>

the Landlord. Any alteration, addition or improvement made by the Tenant after
such consent shall be given, and any fixtures which are installed and would
damage the building if removed, shall at the Landlord's option become the
property of the Landlord upon the expiration or sooner termination of this
Lease, provided, however, that the Landlord shall have the right to require the
Tenant to remove such fixtures, at the Tenant's expense upon expiration or
termination of this Lease, and return the property to its original condition.

                                 PERMITTED USE:

      The premises shall be occupied and used by Tenant for the following
purposes and no others unless such other uses are approved by Landlord in
writing, in advance.

                       a. Light Manufacturing and Storage.

      Tenant agrees not to use said premises, or permit the same or any part
thereof to be used, for the purpose of storing any material or goods which might
in any way prejudice the insurance on said premises or increase the fire hazard
to a greater extent than that necessarily incident to the business for which the
premises are leased as herein before set forth.

                            MAINTENANCE OF PREMISES:

      Tenant shall commit no act of waste and shall take good care of the
premises and the fixtures and appurtenances therein, and shall in the use and
occupancy of the premises, conform to all laws, orders and regulations of
federal, state and municipal governments having jurisdiction. Tenant shall
maintain the interior of said leased premises in good, safe and presentable
condition during the term of the Lease and will surrender the premises in as
good condition as they were at the beginning of the term, reasonable wear and
tear, excepted. All of the property of Tenant remaining on the premises at the
expiration of the Lease or any renewal thereof shall be conclusively deemed
abandoned and may be removed, disposed of or stored by the Landlord at Tenant's
expense. Tenant shall reimburse the Landlord for the cost of such removal and
disposition, including the cost of storage. Landlord shall be responsible for
maintenance and replacement of all mechanical, electrical and plumbing systems,
and for the maintenance of the exterior of the leased premises. Tenant agrees to
provide preventative maintenance for the HVAC equipment by contracting a local
HVAC service company. Landlord's air compressor will remain on site and be
available for Tenant use. All service required to maintain air compressor in
working order will be the responsibility of Tenant.

                           ASSIGNMENT AND SUBLETTING:

      A. Tenant shall have right to sublet part of the premises with the prior
written consent of the Landlord, which consent shall not be unreasonably
withheld.

                                    SERVICES:

      The Tenant will pay the cost of utilities.

      Tenant shall be responsible for arranging for and paying for janitorial
service, trash removal, and exterminating services for the leased premises.

                                                                               2
<PAGE>

                                   INSURANCE:

      Landlord will provide hazard insurance covering the improvements on the
property with coverage equal to the replacement value of the improvements and
general liability covering the common areas.

      The Tenant shall be responsible for obtaining, at his expense, insurance
coverage for the Tenant's personal property stored or used on the premises. No
such coverage will be provided by the Landlord. Tenant shall maintain in force
at all times, at his expense, general liability coverage insurance covering the
leased premises, with limits of at least of $500,000/$1,000,000, naming Landlord
as an additional insured under the policy.

      Landlord and Tenant shall upon the other party's request, furnish
certificates of insurance to the other party for insurance required by this
paragraph.

                                  FIRE CLAUSE:

      In the event that the leased premises shall be destroyed or damaged to
such an extent by fire or other casualty, that they are rendered untenantable,
the Landlord shall have the right to render said premises tenantable by repairs
within ninety (90) days therefrom. During any period of untenantability, the
rent shall not abate. However, if upon the expiration of ninety (90) days from
the date of the incident causing the damage to the leased premises have not been
made habitable by Landlord, either party shall upon written notice to the other,
have the right to terminate this Lease as of the date of such event, and any
rent paid for periods thereafter shall be refunded to the Tenant. In the event
of loss or damage to the premises, each party shall look first to any insurance
in his favor before making any claim against the other party and to the extent
possible without additional cost, each party shall obtain for each policy of
hazard insurance, provisions permitting waiver of any claim against the other
party for loss or damage within the scope of the insurance.

                                  RISK OF LOSS:

      The risk of loss to Tenant's property used or stored upon the leased
premises shall be solely upon the Tenant except for misconduct or gross
negligence by Landlord or Landlord's agents.

                                 SUBORDINATION:

      This Lease shall be subject to and subordinate to the lien of any
mortgage, deed of trust, or other encumbrance now existing or hereinafter placed
upon the premises by the Landlord and Tenant hereby agrees to execute upon the
request of Landlord, any and all instruments necessary to effect such
subordination.

                         ADDITIONAL COVENANTS BY TENANT:

      Tenant shall, at all times, during the term of this Lease, and any
renewals thereof, operate a business on the leased premises and shall not at any
time, display on the premises any sign announcing that the business is moving to
a new location, is going out of business, of that the

                                                                               3
<PAGE>

business is being liquidated or is in bankruptcy, or any similar sign indicating
that the Tenant is ceasing to do business at the leased premises.

                                    DEFAULT:

      Tenant shall be in default of this Lease if:

      A.    The failure by Tenant to make any payment of rent or any other
            payment required to be made by Tenant hereunder, as and when due,
            where such failure shall continue for a period of fifteen (15) days
            after written notice thereof by Landlord to Tenant.
      B.    The failure by Tenant to observe or perform any of the covenants,
            conditions or provisions of this Lease to be observed or performed
            by Tenant (other than described in Subsection A above), where such
            failure shall continue for a period of thirty (30) days after
            written notice thereof by Landlord to Tenant; provided, however,
            that if the nature of Tenant's default is such that more than thirty
            (30) days are reasonably required for its cure, then Tenant shall
            not be deemed to be in default if Tenant commences such cure within
            said thirty (30) day period and thereafter diligently prosecutes
            such cure to completion.

      In the event of Tenant's default, Landlord shall, in addition to all of
the remedies available at law, be entitled to re-enter the premises, make such
repairs and renovations as Landlord in its sole discretion, deems appropriate,
and re-lease the premises to any other party on such terms and conditions as
Landlord, in its sole discretion, deems just and appropriate. The proceeds of
such lease, after payment of Landlord's expenses of renovation, repair and
leasing of the premises, shall be applied to Tenant's account. Landlord shall be
entitled to recover the rent provided for the full lease term, offset only by
rent actually received or by the reasonable rental value of any portion of the
leased premises which are actually occupied by the Landlord for any portion of
the lease term.

      The occurrence of any one or more of the following constitutes a default
by Landlord under this Lease:

      A. If Landlord shall default in the payment when due of any moneys
required to be paid by Landlord under this Lease, and such default shall
continue for a period of thirty (30) days after written notice by Tenant to
Landlord to such default.

      B. If Landlord shall default in the performance of any obligation of this
Lease on Landlord's part to be performed and Landlord shall fail to remedy such
default within thirty (30) days after written notice by Tenant to Landlord, or
is such default is of such a nature that it cannot be completely remedied within
said period of thirty (30) days if Landlord shall not (I) promptly upon the
giving by Tenant of such notice, advise Tenant of Landlord's intention to
institute all steps reasonably necessary to remedy such situation, and (II)
promptly institute and thereafter diligently pursue all steps reasonably
necessary to remedy the same.

      If a default by Landlord occurs, Tenant shall have all rights and remedies
available at law or in equity, including the right to set off against any
amounts due from Tenant to Landlord, the amounts required to cure any default on
the part of Landlord.

                                                                               4
<PAGE>

                               ENTRY BY LANDLORD:

      Landlord may, but shall not be obligated to, enter the demised premises at
any reasonable time during normal business hours, on reasonable notice to Tenant
(except that no notice need be given in case of emergency) for the purposes of
inspection or the making of such repairs, replacements and addition as are
necessary or desirable.

                             CONSTRUCTIVE EVICTION:

      Tenant shall not be entitled to claim a constructive eviction from the
premises unless Tenant shall have first notified Landlord in writing of the
condition or conditions giving rise thereto, and, if the complaints be
justified, unless Landlord shall have failed within a reasonable time after
receipt of notice to remedy such conditions.

                           LANDLORD MAY SHOW PREMISES:

      Landlord may show the premises to prospective purchasers and mortgagees at
a reasonable time, and during the four months prior to expiration and upon
notice of termination of the Lease, to prospective tenants, during business
hours and upon reasonable notice to Tenant.

      Landlord agrees that any sale by Landlord of the demised premises shall be
subject to the terms and provisions of this Lease, and that in the event of any
sale of the Leased Property by Landlord, the purchaser, at such sale or any
subsequent sale of the demised premises shall be deemed, without further
agreement between the parties of their successors in the interest, or between
the parties and any such purchaser, to have assumed and agreed to carry out any
and all of the covenants and obligations of the Landlord under this Lease.

                                QUIET POSSESSION:

      Landlord covenants that if and so long as Tenant pays the rent and
additional rent and perform the covenants hereof, Tenant shall peaceably and
quietly have, hold and enjoy the premises for the term herein provided, subject
to the provisions of this Lease.

                               COVENANT OF LEASE:

      A. Tenant shall not make, or permit to be made, disturbing noise or
interfere with any other businesses operating in the area.

                               ACTS OF INSOLVENCY:

      In the event that the Tenant or any of its guarantors, shall file in any
court a petition of bankruptcy or insolvency or for reorganization or for a
creditors arrangement under any section or sections of the United States
Bankruptcy or any other statute or if a receiver or trustee shall be appointed
for all or a portion of the Tenant's property or if the Tenant or any of its
guarantors shall make an assignment of its asserts for the benefit of creditors,
then this Lease shall, at the discretion of the Landlord, immediately terminate
and this Lease shall not be treated as an asset to the Tenant's estate or the
Landlord may terminate the Tenant's right to occupancy of the

                                                                               5
<PAGE>

premises and re-enter the premises, thereby retaining all of his rights and
remedies against the Tenant.

                                  NOTIFICATION:

      All notices are to be sent to the following:

To Landlord: Alan G. Dillard Jr.
             1000 River Road
             Charlottesville, VA 22901

To Tenant:   Biotage
             1500 Avon Street Extd.
             Charlottesville, VA 22901

                                  MODIFICATION:

      This Lease may be terminated, modified, or otherwise changed only by
written agreement signed by the Tenant and the Landlord.

WITNESS the following signatures and seals:

LANDLORD:                                    ALAN G. DILLARD, JR.

                                             By: /s/ Alan G. Dillard, Jr.
------------------------------                  ------------------------------
            Date

TENANT:                                      BIOTAGE A DIV. OF DYAX CORP.

                                             By: /s/ David Patteson
------------------------------                  ------------------------------
            Date

Tenant shall have a first right of refusal to extend the lease with 90 days'
advance notice prior to the end of the term of the Lease.

Provided that Rent shall increase annually by three percent (3%) beginning upon
completion of the initial term of this Lease.

                                                                              6

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