Configuration of the acetal carbon atom of pyruvic acid acetals in some bacterial polysaccharides |
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| Authors: | Per J Garegg Per-Erik Jansson Bengt Lindberg Frank Lindh Jörgen Lönngren Ingemar Kvarnström Wolfgang Nimmich |
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| Institution: | Department of Organic Chemistry, Arrhenius Laboratory, University of Stockholm, S-106 91 Stockholm Sweden;Department of Chemistry, University of Linköping, S-581 83, Linköping Sweden;Institut für Medizinische Mikrobiologie und epidemiologie Wilhelm-Pieck-Universität Rostock, DDR-25 Rostock 1 German Democratic Republic |
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| Abstract: | The configuration at the acetal carbon atom of pyruvic acid acetals present in some extracellular bacterial polysaccharides has been investigated. Assignment of the absolute configuration was made by comparing signals in the 13C- and 1H-n.m.r. spectra of the polysaccharides with those of model substances. The S-configuration was demonstrated in eight polysaccharides in which pyruvic acid is linked to O-4 and O-6 of D-glucopyranosyl or D-mannopyranosyl residues. The R-configuration was demonstrated in four polysaccharides in which pyruvic acid is linked to O-4 and O-6 of D-galactopyranosyl residues. Consequently, in each of these acetals, which form 1,3-dioxane rings, the methyl group is equatorial and the carboxyl group axial. The S-form was further demonstrated in four polysaccharides in which the pyruvic acid is linked to O-3 and O-4 of D-galactopyranosyl groups. |
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