| abstract |
Branched polyalkylene glycols useful as reagents for chemically modifying physiologically active polypeptides wherein two single-chain polyalkylene glycols are attached to a group having a cyclic structure other than a planar structure and a group reactive with an amino acid side chain, the N-terminal amino group or the C-terminal carboxyl group in a polypeptide or a group which can be converted into such a reactive group is further attached thereto. |