Patent ID: 8492488

Claim:
A polymer conjugate comprising the structure: POLY—[Y—S—S—A] x wherein: POLY is a water soluble polymer; Y has the formula —(CR 1 R 2 ) n —, where n is 4 to 8, each of R 1 and R 2 is independently selected from hydrogen, lower alkyl, lower alkenyl, and a non-interfering substituent, where two groups R 1 and R 2 on different carbon atoms may be linked to form a cycloalkyl or aryl group; S—S is a disulfide group attached to an sp 3 hybridized carbon of Y; and A is a covalently linked residue of a pharmacologically active molecule; and x is 1-25, and if POLY is a linear polyethylene glycol, x=1, and Y is a linear alkyl chain, the POLY has a molecular weight of at least 500, wherein when POLY is a linear polyethylene glycol, at least one R 1 on a carbon adjacent to said disulfide linkage is lower alkyl.