Patent ID: 7214660

Claim:
A covalent conjugate between an erythropoietin peptide and poly(ethylene glycol), wherein said poly(ethylene glycol) is covalently attached to said erythropoietin peptide at a preselected glycosyl or amino acid first residue of said erythropoietin peptide via a first intact glycosyl linking group said covalent conjugate prepared by a method comprising: contacting said erythropoietin peptide with at least one glycosyltransferase and at least one modified sugar donor under conditions suitable for said at least one glycosyltransferase to transfer a sugar moiety of said at least one modified sugar donor to said erythropoietin peptide, wherein said modified sugar moiety comprises at least one modifying group which is a water-soluble polymer, thereby forming said covalent conjugate of said erythropoietin peptide.