Structural determination of the capsular polysaccharide of Streptococcus pneumoniae type 18C (56)

The specific capsular polysaccharide of Streptococcus pneumoniae type 18C (56) contains D-glucose, D-galactose, L-rhamnose, and glycerol residues, and phosphate and O-acetyl groups in the molar ratios of 3:1:1:1:1:1. Accumulated data from methylation analyses of the native and the specifically degraded, native polysaccharide indicated that it is composed of the repeating unit shown; it also contains O-acetyl groups, of undetermined location, in the molar ratio to L-rhamnose of 1:1. (formula; see text).