Determination of the sugar sequences and the glycosidic-bond arrangements of immunogenic heteroglycans.

The complete sugar sequences and glycosidic-bond arrangements have been determined by a combined analytical scheme for a diheteroglycan of D-glucose and D-galactose and a tetraheteroglycan of 6-deoxy-L-talose, L-rhamnose, D-galactose, and D-glucuronic acid. The analytical scheme included methylation analysis by g.l.c. and mass spectrometry, periodate oxidation followed by borohydride reduction and identification of the residual fragments, enzymic hydrolysis followed by characterization of the modified glycan, and chemical degradation followed by characterization of the resulting fragments. The diheteroglycan and the tetraheteroglycan are immunogenic substances on the cell surface of the organisms, and are the group specific carbohydrates in the cell walls of Streptococcus faecalis, strain N, and Streptococcus bovis, strain C3. The combined analytical scheme should be of general applicability for the structural analysis of heteroglycans for which selective-degradation procedures can be devised.