Title : Activation
peptide of human
factor IX has
oligosaccharides O-glycosidically linked to
threonine residues at 159 and 169
Abstract :
- O-Linked oligosaccharide chains were identified in the activation peptide (AP) of human blood coagulation factor IX
- The peptide obtained from human factor IX was separated into three molecular species ( AP alpha , AP beta , and AP gamma) by reversed-phase high-performance liquid chromatography
- Amino acid analysis showed that AP alpha , but not AP beta and AP gamma, contained galactosamine in addition to glucosamine, thereby suggesting the presence of an O-linked sugar chain(s) in the molecule of AP alpha
- A nonapeptide ( AP alpha-D4, residues 157-165 ) and an undecapeptide ( AP alpha-D5, 166-176) derived from AP alpha contained Thr-159 and Thr-169 , neither of which could be identified using a gas-phase protein sequencer
- All other serine and threonine residues serine and threonine residues present in AP alpha were identified by peptide sequencing
- Component sugar and sialic acid analyses of AP alpha-D4 and AP alpha-D5 revealed that they contained 1 mol each of N-acetyl-D-galactosamine (GalNAc), D-galactose (Gal), and sialic acid.
- Fast atom bombardment tandem mass spectrometric analysis of AP alpha-D4 suggested the existence of Gal-GalNAc-Thr, NeuNAc-(Gal-)GalNAc-Thr, and NeuNAc-Gal-GalNAc-Thr structures. Thr , NeuNAc-(Gal-)GalNAc- Thr , and NeuNAc-Gal-GalNAc- Thr structures
- On the basis of amino acid analysis after the isolation of AP alpha , it accounted for approximately 35% of the total activation peptide obtained
- From these results, it was concluded that a part of the activation peptide of human factor IX in circulating blood has tri- and tetrasaccharides O-glycosidically linked to the threonine residues at 159 and 169