A method is provided for preparing a biologically active molecule having an increased
serum half-life. The method involves conjugating a polymer such as polyethylene
glycol to the biologically active molecule. Also provided are polypeptide drugs
having an increased serum half-life, e.g., human urokinase plasminogen activator
(human "uPA" or "hUPA") or a fragment or derivative thereof. Pharmaceutical compositions
containing such molecules and methods of using them to treat uPA-mediated and uPA
receptor-mediated disorders are also provided.
