Structural analysis of N-linked sugar chains of human blood clotting factor IX

The structures of N-glycans of human blood clotting factor IX were studied. N-Glycans liberated by hydrazinolysis were N-acetylated and the reducing-e nd sugar residues were tagged with 2-aminopyridine. The pyridylamino (PA-) sugar chains thus obtained were purified by HPLC. Each PA-sugar chain was a nalyzed by two-dimensional sugar mapping combined with glycosidase digestio n. The major structures of the N-linked suffer chains of human factor IX we re found to be sialotetraantennary and sialotriantennary chains with or wit hout fucose residues. These highly sialylated sugar chains are located on t he activation peptide of the protein.