Title : Identification and structural analysis of
the tetrasaccharide NeuAc alpha(2-->6)Gal beta(1-->4)GlcNAc beta(1-->3)Fuc alpha 1-->O-linked to
serine 61 of human
factor IX
Abstract :
- O-Linked fucose has been found attached to Thr/Ser residues within the sequence Cys-X-X-Gly-Gly-Thr/Ser- Cys in the N-terminal EGF domains of several coagulation/fibrinolytic proteins
- Carbohydrate composition and mass spectrometric analyses of tryptic and thermolytic peptides containing the corresponding site ( Ser-61 ) in the first EGF domain of human factor IX indicated the presence of a tetrasaccharide containing one residue each of sialic acid, galactose, N-acetylglucosamine, and fucose.
- The Ser-61 tetrasaccharide was not susceptible to alpha-fucosidase digestion
- Fragments generated during mass spectrometric analysis indicated that fucose was the attachment sugar residue
- The involvement of fucose in the carbohydrate-peptide linkage was confirmed by two-dimensional 1H NMR spectroscopic analysis of the glycopeptide containing factor IX residues 57-65
- The complete structure of the tetrasaccharide was obtained by methylation analysis and two-dimensional 1H TOCSY and ROESY experiments as NeuAc alpha(2-->6)Gal beta(1-->4)GlcNAc beta(1-->3)Fuc alpha 1-->O-Ser61. Ser61