Characterization of the extracellular, water-insoluble α-D-glucans of oral streptococci by methylation analysis, and by enzymic synthesis and degradation

摘要: Abstract Methylation analysis of water-insoluble α- D -glucans synthesized from sucrose by culture filtrates several strains Streptococcus spp. has proved that all the glucans were highly branched and chains contained (1→6)- (1→3)-linked -glucose residues not involved in branch points. Hydrolysis with a specific endo-(1→3)-α- -glucanase demonstrated majority glucose arranged sequences. -Glucose was major product hydrolysis, small proportion nigerose also released. The use endo-(1→6)-α- similarly indicated sequences (1→6)-linked residues, those branched. Two -glucosyltransferases (GTF-S GTF-I), which reacted to synthesize soluble glucan glucan, respectively, separated S. mutans OMZ176. characterized as (1→6)-α- -glucan, whereas insoluble one relatively linear (1→3)-α- -glucan. hypothesis is advanced glucosyltransferases can transfer means acceptor reactions similar proposed Robyt for dextransucrase, leading synthesis containing both types chain. resulting structure consistent evidence obtained methylation enzymic degradations, explains synergy displayed when two interact sucrose. Variations basic account characteristics sanguis salivarius, strain-dependent diversity glucans.