Glycans from Streptococcal Cell Walls

A complete molecular structure for an antigenic glycan isolated from the cell wall of Streptococcus faecalis is being proposed on the basis of analytical data obtained from methylation, acetolysis, and periodate oxidation experiments and on the basis of the nature of the oligosaccharide fragments isolated from partial acid hydrolysates of the glycan. The antigen is a diheteroglycan composed of a main chain of trisaccharide units, glucose-β(1,6)-glucose-β(1,4)-galactose, joined by β(1,4) linkages with lactosyl and cellobiosyl side chains attached by β(1,4) linkages at alternate glucose residues of the main chain. The proposed structure for the glycan is consistent with the immunochemical properties of the polymer. Quantitative precipitin inhibition studies clearly indicate that lactosyl residues are the immunodominant determinants of the glycan.