The structure of the capsular polysaccharide from Streptococcus pneumoniae type 7B.

The capsular polysaccharide elaborated by Streptococcus pneumoniae type 7B is composed of the following heptasaccharide repeating-units. [formula: see text] The identities and modes of linkage of the constituents were established using sugar, methylation, and phosphorus analysis, together with 1D- and 2D-n.m.r. spectroscopy. The sequence was established from inter-residue n.O.e. data. The structure was corroborated by n.m.r. spectroscopy, f.a.b.-m.s., and methylation analysis of the oligosaccharides isolated after partial acid hydrolysis of the polysaccharide with aqueous 48% hydrogen fluoride. It is suggested that the structural basis for the common antigenic formula in the group 7 serotypes of S. pneumoniae is the disaccharide element alpha-D-GlcpNAc-(1----2)-alpha-L-Rhap-(1----.