Glycans from streptococcal cell walls: An antigenic triheteroglycan of 6-deoxy- l-talose, l-rhamnose and d-galactose from Streptococcus bovis

Abstract

Two antigenic glycans have been isolated from the cell wall of Streptococcus bovis strain C3 by sequential extraction with HCl-KCl buffer of pH 2 and purified by filtration through Bio-gel. Chemical analysis showed that one glycan is a triheteroglycan of d-galactose, l-rhamnose and 6-deoxy- l-talose in the ratio of 2:1:1 and the other is a diheteroglycan of d-glucose and l-rhamnose in the ratio of 1:1. On the basis of the immunochemical data and the nature of acid hydrolytic products from the triheteroglycan, it is proposed that the triheteroglycan consists of a main chain of alternating rhamnose and 6-deoxy-talose residues with side chains of digalactosyl units. The terminal α-linked galactosyl residues are the immunodeterminants of the glycan. The deoxy sugar, 6-deoxy- l-talose, has not been detected previously in streptococcal cell walls and in S. bovis, this sugar is synthesized via the thymidine diphosphate hexose pathway.