Structural elucidation of the specific capsular polysaccharide of Rhodococcus equi serotype 7

Abstract

Structural analysis of the specific capsular polysaccharide produced by Rhodococcus equi serotype 7 indicated it to be a high-molecular-weight 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 composed of the linear repeating trisaccharide units, {A figure is presented} →3)-α-d-Galp-(1→3)-α-d-Manp-(1→3)-α-l-Rhapp-(1→, in which the cyclic pyruvic acid acetal groups bridging the O-4 and O-6 positions of the α-d-Manp residues have the S-configuration. The 1H and 13C NMR spectra of the native and pyruvic acetal-free polysaccharides were fully assigned. © 1994.