STUDIES OF STREPTOCOCCAL CELL WALLS III

Abstract

Quantitative amino acid analyses of trypsin-treated, type 14, group A hemolytic streptococcal cell walls showed. the main components after acid hydrolysis to be glucosamine, rhamnose, glu-tamic acid, lysine, alanine and a small amount of muramic acid. Molar ratios of glutamic acid: lysine: alanine: glucosamine: rhamnose were approximately 1:1:4:1.6:1.4 and the respective weights percent were 12, 11, 30, 24, and 22. The C polysaccharide enzymatically liberated from the cell walls showed the ratios 1:1:4:6:6, with weights percent of 6 for glutamic acid, alanine 15, glucosamine 45 and rhamnose 48. Charcoal treatment of the polysaccharide resulted in a product with the ratios 1:1:4:12:16 and weights percent of 3, 3, 7, 40, 54, indicating a preferential removal of amino acid rich portions of the polysaccharide preparations. Trypsin-treated cell walls of a variant group A streptococcus showed ratios of 1:1:4.0:0.84:4.1, with corresponding percent weights of 8, 6, 16, 18, 40. The variant polysaccharide gave ratios of 1:1:4:1.4:7.5 and the percentages 7, 8, 14, 13, 61. It is concluded that the structural portion of the streptococcal cell wall is composed of a rhamnose and hexosamine-containing polysaccharide linked to a polypeptide made up of glutamic acid, lysine and alanine. The peptide chains are composed of a series of unit hexapeptides, each unit containing one glutamic acid, one lysine and four alanines in undetermined sequence.