ANTI-ENZYME IMMUNITY 359 



could be seen in the form of droplets and fatty acid crystals. The 

 mean ether-extractable fat content (gravimetrically) of normal muscle 

 samples was 7.3 per cent, that of gangrenous muscle samples 19.9 

 per cent, indicating a point of interest in view of the known effect of 

 lecithinase on lipo-proteins. 



When incubated with toxin, slices of rabbit or human muscle were 

 disintegrated, while control slices incubated in toxin neutralized with 

 antitoxin maintained their toughness for days. Toxin-treated muscle 

 was a friable mass of loose and brittle fibers. The treatment of muscles 

 with crystalline trypsin resulted in a semitransparent gelatinous, or 

 white fibrous mass. Microscopically, these muscle-fibres could not be 

 recognized, none the less they were tough and elastic. This gelatinous 

 material, washed free of trypsin, could be completely lysed by toxin; 

 conversely, the mass of fibre left after incubation with toxin could be 

 almost completely digested by trypsin. These facts indicated the pres- 

 ence of two different substances in the muscle, the trypsin-soluble, 

 toxin-insoluble protein of fibre, and the toxin-soluble, trypsin-insoluble 

 frame-work on which the structural integrity of the muscle depends. 

 These investigators reported that the toxin of CI. welchii exercises a 

 "collagenase" activity which was believed to be directly involved in 

 the muscle destruction in gas-gangrene. 



In connection with the characterization of certain proteolytic en- 

 zymes as collagenase, the nature of the substrate and the methods used 

 for its preparation must be a consideration. Neuman and Tytell (1950) 

 reported that collagens prepared by more drastic means and commercial 

 hide powder were highly susceptible to attack by the proteolytic en- 

 zymes. Denaturation of collagen by heat and urea produces general 

 susceptibility to common proteolytic enzymes. On the other hand, col- 

 lagens from various sources prepared by mild processes designed not 

 to alter the properties were found to be resistant to the action of trypsin, 

 chymotrypsin, and papain. These collagens were readily attacked (solu- 

 bilized) by the proteolytic enzymes of CI. histolyticum and by pepsin. 

 The proteolytic activity of CI. 'perfringens filtrates are found to be 10 

 to 20 fold weaker than those of CI. histolyticum filtrates in the degra- 

 dation of collagen. 



Collagen is a protein forming the chief constituent of connective 

 tissue and the organic substance of bones. Collagenous fibres when 

 boiled with water dissolve and yield a colloidal solution of animal glue 



