326 IMMUNO-CATALYSIS 



that the hemolysin contains a -SH?^-S-S- oxidation-reduction system, 

 and that this system must be in the -SH form in active hemolysin. 

 However, the high content of sulfur, only a part of which existed as 

 -SH groups, suggested another possible role for this element. 



The partially purified hemolysin was neutralized by various anti- 

 sera, as was the untreated supernatant broth of cultures of hemolytic 

 streptococci. This neutralization was independent of purification or 

 reduction of the hemolysin, and was not accompanied by precipitation, 

 in the available range of concentration of the reagents. For a discussion 

 of the observations regarding the in vitro formation of streptolysin S 

 the reader is referred to an article by Bemhermer (1949). 



a. Streptolysin O. Herbert and Todd (1941) reported the follow- 

 ing findings from a comprehensive study of the reversibly oxidizable 

 streptolysin of Group A hemolytic streptococci. This hemolysin is pro- 

 duced by most strains of Group A streptococci when grown in a serum- 

 free medium such as glucose-bicarbonate-phosphate-broth; it is also pro- 

 duced by Group C strains from human infections and by Group G 

 strains, but not by streptococci of other groups. The streptolysins pro- 

 duced by all types and strains of Group A streptococci are serologically 

 identical. 



Streptolysin O was active only in the presence of certain reducing 

 agents, such as thiolacetic acid, and it was found necessary to add these 

 to the reaction system. The purification of the hemolysin involved 

 fractionation with ammonium sulfate, adsorption and elution from 

 calcium phosphate gel, followed by adsorption and elution from 

 alumina Cy. The purified hemolysin contained 3050 hemolytic units, 

 H.U., per mg. by dry weight; or 1 H.U. contained 0.000,05 mg. of 

 nitrogen, a 10-fold greater purification than that of Smythe and Harris 

 (1940). The purified hemolysin contained: C, 46.7; H, 6.8; N, 16.8; 

 S, 2.34; P, 0.053; ash, 3.6 per cent. The total carbohydrate was 2.6 

 per cent. It gave the usual protein tests. Boiling for two minutes caused 

 complete and irreversible inactivation; the same result was obtained 

 on treatment with strong acids and alkalis. 



The purified preparations of streptolysin O were neutralized by 

 antistreptolysin O to the same extent as the crude preparations. They 

 were neutralized by antisera to CI. welchii ^-hemolysin, but not by 

 antisera to welchii a-hemolysin. The a-hemolysin of CI. welchii hy- 

 drolyzes lecithin, but streptolysin does not give this reaction. No trace 



