The capsular polysaccharide antigen of Neisseria meningitidis group I was isolated by Cetavlon precipitation and purified by ion-exchange chromatography. The structure of the I polysaccharide was determined largely by comprehensive proton and carbon-13 nuclear magnetic resonance studies in which both one-dimensional and two-dimensional experiments were carried out directly on the I polysaccharide. The I polysaccharide is composed of the repeating unit →4)α-L-GulpNAcA(1→3)[4-OAc]β-D-ManpNAcA(→ in which the former residue adopts the 4C1 (L) conformation and the latter residue adopts the 4C1 (D) conformation. The one-bond coupling between the anomeric carbon and proton (1J13C,H) of the 2-acetamido-2-deoxy-β-D-mannuronopyranosyl residue is not consistent with its β-D configuration. This anomalous value of 1J13C,H for this residue is due to through-space anisotropy effects on its anomeric proton, generated by the proximity of the carboxyl group of the neighboring 2-acetamido-2-deoxy-α-L-guluronopyranosyl residue. The O-acetyl substituents of the I polysaccharide are essential for its antigenicity to group I polysaccharide-specific antibodies.
NCBI PubMed ID: 3935165Publication DOI: 10.1021/bi00341a046Journal NLM ID: 0370623Publisher: American Chemical Society
Institutions: Division of Biological Sciences, National Research Council of Canada, Ottawa, Ontario KIA OR6, Canada, and Bureau of Microbiology, Laboratory Center for Disease Control, Ottawa, Ontario K1 A OL2, Canada
Methods: 13C NMR, 1H NMR, NMR-2D, methylation, GLC-MS, partial acid hydrolysis, sugar analysis, acid hydrolysis, GLC, carboxyl reduction, de-O-acetylation, NMR-1D
Found