INHIBITION OF PROTEINASES OF CERTAIN CLOSTRIDIA BY SERUM

Some members of the gas-gangrene group, such as Clostridium histolyticum, secrete proteolytic enzymes which cause much tissue damage in vivo. However, certain non-pathogenic Clostridia, such as Clostridium sporogenes, produce proteolytic enzymes which are as active as those of Clostridium histolyticum in the hy-drolysis of gelatin or casein, but which are relatively impotent in vivo. In regard to the pH optima and activation behavior, no differences have been found between the proteinases of the pathogenic and the non-pathogenic Clostridia (Weil, Kocholaty and Smith, 1939). Pozerski and Blanc (1920) reported that the proteinase of C. sporogenes was inhibited by normal horse serum, while that of C. histolyticum was not. This suggested that absence of inhibi-tion by normal serum of the exocellular proteinases of this group of organisms might be correlated with the pathogenicity of the strain producing the proteinase. Evidence in support of this possibility appeared when, during the prosecution of this study, Grassmann (1938) reported the inhibition of the proteinase of Clostridium botulinum by normal horse serum, but could find no inhibition of the enzymes of Clostridium welchii. The enzymes of the latter organism, how-ever, were inhibited by immune serum. MATERIALS AND METHOD The organisms used in this study, with the exception of the strain of C. histolyticum, were obtained from the American Typ