Glycans from streptococcal cell-walls: the molecular structure of an antigenic diheteroglycan of D-glucose and L-rhamnose from Streptococcus bovis

Abstract

The monosaccharide sequence and glycosidic bond-types have been determined for an antigenic diheteroglycan of D-glucose and L-rhamnose from the cell wall of Streptococcus bovis, strain C3, by use of an integrated analytical scheme based on methylation analysis, periodate oxidation, oxidation with chromium trioxide, enzymic hydrolysis, and chemical degradation. A typical molecule of the glycan consists of a main chain of L-rhamnosyl residues and isomaltose side-chains, with 16 repetitions of the structure, -α- L-rhamnosyl-(1→3)-[α- D)-glucosyl-(1→6)-α- D-glucosyl-(1→2)]-α- L-rhamnosyl-(1→2)-α- L-rhamnosyl-, linked alternately by α- L-(1→3) and α- L-(1→2) linkages. The isomaltose side-chains of the glycan are the immunodeterminant groups. The new antigenic glycan is ideally suited for use in the preparation of anti-isomaltose antibodies, which should be of value in the detection of other antigens having isomaltose determinants.