Characterisation by mass spectrometry and 500‐MHz proton nuclear magnetic resonance spectroscopy of penta‐ and hexasaccharide chains of human foetal gastrointestinal mucins (meconium glycoproteins)

Abstract

Structural studies using liquid secondary ion mass spectrometry, gas liquid chromatography/mass spectrometry and 500‐MHz ¹H NMR are described of the major penta‐ and hexasaccharides of a fraction of human foetal gastrointestinal mucins. Glycoproteins from a blood group H active meconium pool were studied after depletion of Ii antigenic activities by immunoaffinity chromatography and treatment with mild acid hydrolysis to reduce the chain heterogeneity. Oligosaccharides were released by mild alkali/borohydride degradation and purified by Bio‐Gel P4 chromatography and HPLC. Eleven penta‐ and hexasaccharides have been fully characterised as a result of this study and one previous report [Hounsell et al. (1988) Biochem. J. 256, 397–401] and information obtained on additional oligosaccharides present in small amounts. These oligosaccharides show the following features: Sequences in these oligosaccharides not commonly found in mucins so far studied are chain‐terminating GlcNAα1–4Gal. repeating‐type‐I (Galβ1–3GleNAc) backbones, the backbone branch GlcNAcβ1–6(GlcNAcβ1–3)Gal and the backbone sequence GlcNAcβ1–6Galβ1‐ in the absence of a substitutent at C3 of galactose.