The present invention provides conjugates between Factor IX and PEG moieties. The conjugates are linked via a glycosyl linking group interposed between and covalently attached to the peptide and the modifying group. Conjugates are formed from glycosylated peptides by the action of a glycosyltransferase. The glycosyltransferase ligates a modified sugar moiety onto a glycosyl residue on the peptide. Also provided are methods for preparing the conjugates, methods for treating various disease conditions with the conjugates, and pharmaceutical formulations including the conjugates.
