Disclosed are compounds that comprise: (i) a Kunitz domain polypeptide
that comprises a Kunitz domain that binds to and inhibits a protease; and
(ii) a plurality of polyethylene glycol moieties attached to the Kunitz
domain polypeptide. Each accessible primary amine of the Kunitz domain
polypeptide can be attached to one of the moieties. Also disclosed are
related methods.