High prevalence of 2-mono- and 2,6-di-substituted manol-terminating sequences among O-glycans released from brain glycopeptides by reductive alkaline hydrolysis. |
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Authors: | W Chai C T Yuen H Kogelberg R A Carruthers R U Margolis T Feizi A M Lawson |
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Institution: | The Glycosciences Laboratory, Imperial College School of Medicine, Northwick Park Hospital, Harrow, Middlesex, UK. |
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Abstract: | Di- to heptasaccharides isolated from total nondialyzable brain glycopeptides after release by alkaline borohydride treatment have been subjected to mass spectrometric and nuclear magnetic resonance spectroscopic analyses supplemented by TLC-MS analyses of derived neoglycolipids. A family of Manol-terminating oligosaccharides has been revealed which includes novel sequences with a 2, 6-disubstituted Manol: In contrast to the Manol-terminating HNK-1 antigen-positive chains described previously that occur as a minor population Yuen, C.-T., Chai, W., Loveless, R.W., Lawson, A.M., Margolis, R.U. & Feizi, T. (1997) J. Biol. Chem. 272, 8924-8931], the above oligosaccharides are abundant. The ratio of these compounds to the classical N-acetylgalactosaminitol-terminating oligosaccharides is about 1 : 3. Thus, there appears to be in higher eukaryotes a major alternative pathway related to the yeast-type protein O-mannosylation, the enzymatic basis and functional importance of which now require investigation. |
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