NMR studies of mannitol-terminating oligosaccharides derived by reductive alkaline hydrolysis from brain glycoproteins Original Research Article

Interest in the characterisation of O-mannosyl glycan structures has been stimulated following the identification of mannitol-terminating oligosaccharides among the chains released from mammalian proteins in nervous and muscle tissues, and by the discovery of a putative human O-mannosyl transferase. Several mass spectrometry methods have been applied to structure elucidation particularly when low amounts of oligosaccharide are available for analysis. However, when sufficient amounts are available, a combination of through-bond homo- and heteronuclear, and of through-space homonuclear NMR experiments permit the complete identification of these oligosaccharide sequences. We describe here the assignment of 1H and 13C NMR chemical shifts from such experiments for four mannitol-terminating oligosaccharide alditols, GlcNAcβ-(1→2)Manol, Galβ-(1→4)GlcNAcβ-(1→2)Manol, Galβ-(1→4)[Fucα-(1→3)]GlcNAcβ-(1→2)Manol and NeuAcα-(2→3)Galβ-(1→4)GlcNAcβ-(1→2)Manol; that were released from brain glycopeptides by alkaline borohydride treatment.