STUDIES OF STREPTOCOCCAL CELL WALLS V

Abstract

Quantitative amino acid analyses were made on cell walls and protein fractions of cell walls from a virulent, type 14 group A Streptococcus (strain Q496) in an attempt to determine any changes in the composition of the streptococcal cell wall which could be correlated with virulence or antigenicity. The amino acid composition and content of the trypsin resistant protein of the cell walls of the virulent strain Q43x and the avirulent strain Q496 were found to be identical. Small quantitative differences and no qualitative differences in the amino acid composition of the cell walls of these strains were detected. The M protein of the virulent strain Q43x and a comparable protein fraction without M activity isolated from the avirulent strain Q496 showed many similarities in composition, however, the M protein contains significantly larger amounts of lysine and aspartic acid. Neither protein fraction was found to be representative of the trypsin-labile protein of their respective cell walls. The data presented indicate that the changes in the configuration of the proteins of the cell walls which are associated with the marked differences in the antigenicity and possibly the virulence of the streptococcal cell are not accompanied by any large changes in amino acid composition.