Patent ID: 8835599

Claim:
A polymer reagent having a structure according to the following formula: wherein: each POLY 1 , which may be the same or different, is a water-soluble and non-peptidic poly(alkylene glycol); each X 1 , X 2 , and X 3 , which may be the same or different, is a spacer moiety; each L 3 , which may be the same or different, are linkages that are optionally cleavable in vivo; each Z 4 , which may be the same or different, is a capping group or a functional group; each a, b, and c, which may be the same or different, is either zero or one; R comprises two lysine residues linked by amide linkages to a linker of an aliphatic carbon chain comprising a disulfide bond; and p is an integer in the range of 2-32, wherein the polymeric reagent is not in the form of a hydrogel.