Structural elucidation of the capsular polysaccharide antigen of Neisseria meningitidis serogroup Z using 13C nuclear magnetic resonance

The capsular polysaccharide antigen from Neisseriameningitidis serogroup Z contains equimolar quantities of 2-acetamido-2-deoxy-D-galactose, glycerol, and phosphate. Carbon-13 nuclear magnetic resonance indicates that the polysaccharide is composed by a repeating unit of 1′-O-2-acetamido-2-deoxy-α-D-galactopyranosyl-glycerol joined through phosphate diester groups at O-3′ of glycerol and O-3 of the galactosamine residue. Assignments of the signals in the carbon-13 nuclear magnetic resonance spectrum were made by consideration of the previously assigned signals of related monomers and oligomers. When applied to a Karplus type relationship the values of the 3J(13C–31P) coupling constants were consistent with the polysaccharide having an extended conformation.