Type-Specific and Non-Type-Specific Reactions of Purified M Protein Preparations

M proteins of type 1 and type 12 Streptococcus pyogenes were extracted by means of phage-associated lysin and purified by ion-exchange chromatography on CM and DEAE cellulose. Molecular weight distributions were studied by gel chromatography on Biogel A 0.5 m in a 6 molar urea solution and by SDS electrophoresis. Serological activities were studied by the complement-fixation reaction and immunodiffusion and were compared with the estimated molecular weights. Type-specific and non-specific activity was found to be located on the same polypeptide chain of a size of 2 × 10⁴ daltons (type 1) and 1.5 × 10⁴ daltons (type 12). These serologically active chains are in preparations purified by Chromatographic methods accompanied by polypeptides of different sizes which are held together by noncovalent bonds thus forming molecules above 4 × 10⁴ daltons.