CHARACTERIZATION BY MASS-SPECTROMETRY AND H-1-NMR OF NOVEL HEXASACCHARIDES AMONG THE ACIDIC O-LINKED CARBOHYDRATE CHAINS OF BOVINE SUBMAXILLARY MUCIN

The acidic oligosaccharide alditols released from bovine submaxillary-gland mucin by Carlson degradation were investigated by a combination of liquid secondary-ion mass spectrometry, methylation analysis and H-1-NMR. Among the largest structures identified were four branched hexasaccharides, three of them novel, comprising two separate pairs of structures. One pair contained the sequence Fuc(alpha-1-2)Gal(beta-1-4)[Fuc(alpha-1-3)]GlcNAc(beta-1-) (Fuc, L-fucose), at C3 of N-acetylgalactosaminitol and differed only by substitution at C6 by N-acetylneuraminic or N-glycolylneuraminic acid. The other pair also differed in substitution of the sialic acid linked at C6 and contained the GalNAc-(alpha-1-3)[Fuc(alpha-1-2)]Gal(beta-1-4)GlcNAc(beta-1-), sequence at C3 of N-acetylgalactosaminitol. The Lewis(y) and blood-group-A determinants of these sequences have not been found previously in the acidic oligosaccharides of bovine submaxillary-gland mucin, although they have recently been characterised in the neutral chains of bovine submaxillary-gland mucin.