A poly(ethylene glycol) derivative is disclosed that is activated with a sulfone
moiety for selective attachment to thiol moieties on molecules and surfaces. The
activated PEG is water soluble, hydrolytically stable for extended periods, and
forms hydrolytically stable linkages with thiol moieties. The linkages generally
are not reversible in reducing environments. The PEG derivative is useful for modifying
the characteristics of substances including modifying biologically active molecules
and surfaces for biocompatibility. Methods for synthesizing the active PEG and
for preparing conjugates of the active PEG and other substances, including biologically
active substances, are also disclosed.
