Structures of the asparagine-linked sugar chains of human chorionic gonadotropin.
The asparagine-linked sugar chains of human chorionic gonadotropin were released from the polypeptide moiety by hydrazinolysis followed by N-acetylation and NaB3H4 reduction. More than 90% of the released radioactive oligosaccharides contained N-acetylneuraminic acid residues. After removal of N-acetylneuraminic acid residues by sialidase treatment, two neutral oligosaccharide fractions were obtained by paper chromatography. Sequential exoglycosidase digestion revealed that one of them was a mixture of two neutral oligosaccharides. The complete structures of the three oligosaccharides were elucidated by methylation analysis. It was confirmed that all the N-acetylneuraminic acid residues of the asparagine-linked sugar chains of human chorionic gonadotropin occur as NeuAc alpha 2 leads to 3Gal groupings by comparing the methylation analysis data for the acidic oligosaccharide mixture before and after sialidase treatment. Based on these results, the structures of the asparagine-linked sugar chains of human chorionic gonadotropin were confirmed to be +/- NeuAc alpha 2 leads to 3Gal beta 1 leads to 4GlcNAc beta 1 leads to 2Man alpha 1 leads to 6(NeuAc alpha 2 leads to 3Gal beta 1 leads to 4GlcNAc beta 1 leads to 2Man alpha 1 leads to 3)Man beta 1 leads to 4GlcNAc beta 1 leads to 4(+/- Fuc alpha 1 leads to 6)GlcNAc and Man alpha 1 leads to 6(NeuAc alpha 2 leads to 3 Gal beta 1 leads to 4 GlcNAc beta 1 leads to Man alpha 1 leads to 3)Man beta 1 leads to 4 GlcNAc beta 1 leads to 4GlcNAc.
D001216:Asparagine; D001665:Binding Sites; D002241:Carbohydrates / Q000032:analysis*; D006063:Chorionic Gonadotropin / Q000032:analysis*; D006026:Glycoside Hydrolases; D006801:Humans; D008722:Methods; D008745:Methylation; D009005:Monosaccharides / Q000032:analysis; D009439:Neuraminidase; D009844:Oligosaccharides / Q000032:analysis
D002241:Carbohydrates; D006063:Chorionic Gonadotropin; D009005:Monosaccharides; D009844:Oligosaccharides; D001216:Asparagine; D006026:Glycoside Hydrolases; D009439:Neuraminidase