Structural investigation of Klebsiella K-type 4 capsular polysaccharide

The structure of the capsular polysaccharide from Klebsiella type 52, using the computerised approach CASPER and NMR spectroscopy

The structure of the capsular polysaccharide from Klebsiella type 52 has been elucidated using an improved and extended version of the computerised approach CASPER and NMR spectroscopy as principal methods. A previous suggestion to the structure but without the anomeric prefixes, could be shown correct [H. Björndal et al., Carbohydr. Res., 31 (1973) 93-100]. The polysaccharide has a hexasaccharide repeat with the following structure: [formula: see text]

Structure of the capsular polysaccharide of Klebsiella ozaenae serotype K4 containing 3-deoxy-D-glycero-D-galacto-nonulosonic acid

The acidic capsular polysaccharide from the museum strain 2211 of Klebsiella ozaenae serotype K4 is built up of pentasaccharide repeating-units that contain residues of D-glucose, D-mannose, D-glucuronic acid, and 3-deoxy-D-glycero-D-galacto-nonulosonic acid (Kdn) in the ratios 2:1:1:1, as well as an O-acetyl group. The last-named sugar, which is reported in bacterial polysaccharides for the first time, was identified as the methyl (methyl 3-deoxynonulopyranosid)onate obtained by methanolysis of the polysaccharide. On the basis of the results of partial acid hydrolysis, Smith degradation, and computer-assisted 13C-n.m.r. analysis, it was concluded that the capsular polysaccharide has the following structure: (formula see text)