Protoplast membranes from Streptococcus pyogenes incorporated rhamnose into a preexisting polysaccharide when incubated with thymidine diphosphate rhamnose-C(14). This polysaccharide, when extracted from the membranes, did not give a precipitin reaction with group A antisera, but could be coprecipitated with added group A polysaccharide by acetone. It is presumed to be a precursor to group specific polysaccharide of the streptococcal cell wall.

A kinase from Streptococcus pyogenes which catalyzes adenosine triphosphate-dependent phosphorylation of D-glucose and N-acetyl-D-glucosamine has been purified 1,500-fold. The ratio of the enzymatic activity on both substrates remained constant throughout the fractionation.

Glucose-1_"4C and acetylglucosamine-1_14C were added singly and together with equal amounts of the unlabeled reciprocal to Brain Heart Infusion and used for the culture of Streptococcus pyogenes. The labeling pattern of the rhamnose, glucosamine, and muramic acid in the cell wall supported an intermediary role for acetylglucosamine in providing the C1-C6 moiety of muramic acid. Although radioactivity in the C2-C9 portion of muramic acid suggested that some of the lactyl group (C7-C9) came from glycolytic products, there was also considerable contribution to it from noncarbohydrate sources. Using cell-free extracts, we were unable to demonstrate biosynthesis of acetylmuramic acid, either free or nucleotide-bound,

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