360 IMMUNO-CATALYSIS 



or gelatin. The collagenous fibres by X-ray diffraction methods (Ast- 

 bury and Bell, 1940) are found to be composed of parallel bundles of 

 long chains of polypeptides. The main features of the X-ray photo- 

 graphs of collagen fibres and oriented gelatin are reported to be the 

 same (Astbury, 1943). The amino acid composition of collagen and 

 gelatin is likewise reported to be essentially the same. Collagen has 

 been reported to be digestible slowly in pepsin-hydrochloric acid solu- 

 tion but by trypsin only at temperatures above 40° C. or after previous 

 action of pepsin in hydrochloric acid solution. The collagenous 

 bundles, which are digestible by pepsin, are, however, resistant to 

 alkaline trypsin solution. The collagenase activity of CI. welchii toxin 

 is found to be optimal at pH 5.5. The above facts may suggest that the 

 "collagenase" activity of CI. welchii may resemble that of pepsin. This 

 activity is neutralized by CI. welchii type A antisera. 



Oakley, Warrack and van Heyningen (1946) reported collagenase 

 as an additional toxin immunologically distinct from a- toxin, /8-toxin 

 and hyaluronidase. This toxin which is capable of breaking down 

 muscle fibres by attacking their collagen and reticulin scaffolding was 

 believed to be responsible for the pulping of muscle seen in human gas- 

 gangrene. They reported that CI. welchii type A filtrates in which all 

 the a-toxin had been neutralized still disintegrated muscle, while 

 filtrates in which all the collagenase (x-toxin) was neutralized had no 

 muscle disintegrating power, though a large amount of a-toxin may still 

 be present. In this connection it may be mentioned that Maschmann 

 (1937) had previously reported that CI. welchii toxin exercises pro- 

 teolytic activity which was specifically neutralizable (or was inhibited) 

 by antitoxic horse sera (p. 256). 



In the evaluation of the above observations, the following findings 

 are of interest. Evans (1947) stated that neither ^S-antihemolysin, anti- 

 hyaluronidase, nor anti-collagenase enhance the protective properties 

 of a-antitoxin. Anti-serum containing a-antitoxin and no anti-colla- 

 genase was found to be highly effective in protecting guinea pigs 

 against infection, whereas an antiserum containing anti-collagenase but 

 not a-antitoxin was able neither to protect against infection nor enhance 

 the protective properties of a-antitoxin. While Evans recognizes that 

 the rapid spread of the disease may be associated with hyaluronidase 

 production and that muscle destruction may be a result of the action of 

 collagenase, he does not find any evidence to support the view that 



