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

Interest in the characterisation of O-mannosyl glycan structures has been s timulated following the identification of mannitol-terminating oligosacchar ides among the chains released from mammalian proteins in nervous and muscl e tissues, and by the discovery of a putative human O-mannosyl transferase. Several mass spectrometry methods have been applied to structure elucidati on particularly when low amounts of oligosaccharide are available for analy sis. However, when sufficient amounts are available, a combination of throu gh-bond homo- and heteronuclear, and of through-space homonuclear NMR exper iments permit the complete identification of these oligosaccharide sequence s. We describe here the assignment of H-1 and C-13 NMR chemical shifts from such experiments for four mannitol-terminating oligosaccharide alditols, G lcNAc beta-(1 --> 2)Manol, Gal beta-(1 --> 4)GlcNAc beta-(1 --> 2)Manol, Ga l beta-(1 --> 4)[Fuc alpha (1-->3)]GlcNAc beta-(1 --> 2)Manol and NeuAc alp ha-(2-->3)Gal beta-(1 --> 4)GlcNAc beta-(1 --> 2)Manol, that were released from brain glycopeptides by alkaline borohydride treatment. (C) 2001 Elsevi er Science Ltd. All rights reserved.