Structure of the capsular polysaccharide of Clostridium perfringens Hobbs 5 as determined by NMR spectroscopy

The complete primary structure of the capsular polysaccharide of Clostridium perfringens Hobbs 5, an anaerobic bacterium implicated in food poisoning, was determined. The polysaccharide was isolated from C. perfringens Hobbs 5 cells, after deproteination, by ethanol precipitation and by ion-exchange chromatography. The polysaccharide was comprised of glucose, galactose, mannose, N-acetylglucosamine, N-acetylgalactosamine, and glucuronic acid, in equimolar ratios. Sequence and linkage assignments of the glycosyl residues were obtained by NMR spectroscopy, specifically by the combination of two-dimensional homonuclear TOCSY and NOESY experiments and heteronuclear (1H, 13) multiplequantum coherence (HMQC, HMQC-COSY, HMQC-TOCSY and HMBC) experiments. Thus, the envelope polysaccharide of C. perfringens Hobbs 5 was found to be a polymer composed of a hexasaccharide repeating unit with the following structure: [→ 4)Glcpβ(1 → 3)GalpNAcβ(1 → 4)GlcpA β(1 → 3)GlcpNAcβ(1 → 2)Galpα(1 → 3)Manpβ(1 → )]nThis structure is novel among bacterial cell-surface polysaccharides, and it is the first of many serotypically distinct capsular polysaccharides of C. perfringens to be described.NMR spectroscopy revealed that the capsular polysaccharide of the title organism was a hexasacchar-ide repeating unit: [→ 4)Glc pβ(1 → 3)Gal pNAcβ(1 → 4)Glc pAβ(1 → 3)Glc pNAcβ(1 → 2)Gal pα(1 → 3)Man pβ(1 →)]n