STRUCTURAL ELUCIDATION OF THE SPECIFIC CAPSULAR POLYSACCHARIDE OF RHODOCOCCUS-EQUI SEROTYPE-7

Structural analysis of the specific capsular polysaccharide produced b y Rhodococcus equi serotype 7 indicated it to be a high-molecular-weig ht polymer consisting of equal molar amounts of D-galactose, D-mannose , L-rhamnose, and pyruvic acid. By employing a combination of chemical and NMR techniques, it was established that the polysaccharide is com posed of the linear repeating trisaccharide units, [GRAPHICS] in which the cyclic pyruvic acid acetal groups bridging the O-4 and O-6 positi ons of the alpha-D-Man p residues have the S-configuration. The H-1 an d C-13 NMR spectra of the native and pyruvic acetal-free polysaccharid es were fully assigned.