Glycans from streptococcal cell walls: The molecular structure and immunological properties of an antigenic glycan from Streptococcus bovis

Abstract

The molecular structure and immunological properties of an antigenic glycan from the cell wall of Streptococcus bovis, strain C3, a member of the Group D Streptococci, have been determined by methylation analysis, periodate oxidation, and hapten inhibition methods. The glycan is shown to be a tetraheteroglycan composed of 6-deoxy- l-talose, l-rhamnose, d-galactose, and d-glucuronic acid. The sugar sequence and the types of glycosidic linkages of the glycan are: a main chain of l-rhamnosyl-(1,3)- d-galactosyl- (1,2)- l-rhamnosyl-(1,3)-6-deoxy- l-talosyl-(1,3)- units with d-glucuronosyl residues attached to position 4 of the first rhamnose of each repeating unit of the main chain. The d-glucuronic acid moiety is the primary immunodeterminant group of the glycan. On the basis of hapten inhibition data, it has been concluded that the binding of the antigen to the antibody occurs at the hydroxyl groups at positions 2 and 3 and the carboxyl group at position 6 of the d-glucuronic acid moieties. The antigen has been used to prepare antiserum with anti-glucuronic acid antibodies.