Cyanide-sensitive Bacterial Respiratory Systems

In previous communications (Sevag and Shelburne, 1942) it was shown that sulfonamide drugs inhibited the aerobic respiration and anaerobic glycolysis of Streptococcus pyogenes and the respiration of pneumococcus Type 1. The inhibition of respiration could take place in the absence of growth. In the presence of growth the inhibition of respiration and of growth occurred to the same relative extent. I t is, therefore, evident that the sulfonamide drugs interfered primarily with the respiratory enzyme systems of the bacteria studied. To dete:mine which enzyme systems are inhibited by the sulfonamide drugs, it is necessary to learn the nature of the catalysts associated with the respiratory functions of these organisms. The present study shows that Streptococcus pyogenes and pneumococcus Type 1 contain cyanide-sensitive respiratory systems which are different from the usual cytochrome c-cytochrome oxidase system. I The respiratory systems of these bacteria appear to be similar to that found by Keilin and Harpley (1941) in B. coli.