Patent ID: 8133865

Claim:
A compound having the following structure: wherein: POLY' is a first water-soluble polymer; POLY 2 is a second water-soluble polymer; X 1 is a first spacer moiety; X 2 is a second spacer moiety; H α is an ionizable hydrogen atom; R 1 is H or an organic radical; R 2 is H or an organic radical; (a) is either zero or one; (b) is either zero or one; R e1 , when present, is a first electron altering group; R e2 , when present, is a second electron altering group; Y 1 is O or S; Y 2 is O or S; and (vWF/F8) is a residue of an amine-containing biologically active agent selected from the group consisting of a von Willebrand Factor moiety and a Factor VIII moiety, wherein the amine-containing biologically active agent is liberated from the compound in its native form under physiological conditions and is bioactive.