title: Structural elucidation of a water-insoluble glucan produced by a cariogenic oral Streptococcus.
abstract: The structure of a water-insoluble polysaccharide produced by the D-glucosyl-transferase of Streptococcus mutans 6715 has been elucidated through periodate oxidation, Smith degradation, dextranase digestion, concanavalin A binding studies, and methylation combined with g.l.c.-m.s. analysis. These studies show that the D-glucan is comprised of 67% alpha-(1----3) linkages in a contiguous backbone with the remaining 33% as alpha-(1----6) linkages, possibly as linear residues extending from alpha-(1----6) branch points. Of the residues, 14% are branch points and the ratio of linear alpha-(1----3) residues in the backbone to alpha-(1----6) residues in the side chain was found to be 5:2. Dextranase digestion and Smith degradation both gave rise to a high-molecular-weight fraction that is only alpha-(1----3) linked.
mesh_terms: D002236:Carbohydrate Conformation; D002849:Chromatography, Gas; D003731:Dental Caries / Q000382:microbiology*; D006801:Humans; D006868:Hydrolysis; D011134:Polysaccharides / Q000096:biosynthesis / Q000302:isolation & purification*; D013290:Streptococcal Infections / Q000382:microbiology*; D013291:Streptococcus / Q000378:metabolism*
chemical_list: D011134:Polysaccharides