Characterisation by mass spectrometry and 1H‐NMR of novel hexasaccharides among the acidic O‐linked carbohydrate chains of bovine submaxillary mucin

Abstract

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 1H‐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(α1–2)Gal(β1–4)[Fuc(α1–3)]GlcNAc(β1–) (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(α1–3)[Fuc(α1–2)]Gal(β1–4)GlcNAc(β1–), sequence at C3 of N‐acetylgalactosaminitol. The Lewisy 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. Copyright © 1992, Wiley Blackwell. All rights reserved