202 IMMUNO-CATALYSIS 



proteins plays a role. This relationship to enzyme activity has been 

 discussed by Barron (1943), and to the denaturation and properties 

 of proteins, by Anson (1945). The role of the SH group in the activi- 

 ties of succinoxidase, phosphoglyceraldehyde dehydrogenase, phospho- 

 glucomutase, and the pyruvate oxidase system has been emphasized. 

 It is common practice to activate papain by certain reducing agents, 

 suggesting, perhaps, a role for SH groups in this enzyme. /^-Amylase 

 (from barley and malted barley) activity was found by Weill and Cald- 

 w^ell (1945) to be associated with SH groups. The inactivation of the 

 enzyme by dilute iodine, ferricyanide and cupric ion was reversed by 

 hydrogen sulfide. The enzyme was irreversibly inactivated by treatment 

 with iodoacetamide, which, as is known, forms an irreversible deriva- 

 tive with the SH groups. 



Micheel and Bischoff (1937) reported that the reduction of crotoxin 

 by means of cuprous oxide, cysteine and a stream of oxygen inactivates 

 the venom by converting the R-S-S-R to RSH groupings. Sulfu- 

 rous acid alone was capable of inactivating the venom in this manner. 

 A crystalline product derived from crotoxin (rattlesnake venom) was 

 found to contain 4 per cent sulfur existing in -S-S- linkages. (Slotta 

 and Fraenkel-Conrat, 1938). Reduction with cysteine of this product 

 likewise destroyed reversibly the toxic activity in a manner comparable 

 to the reversible inactivation of insulin (du Vigneaud et at, 1931- 

 1932). De (1940) observed that cobra hemolysin is reversibly inacti- 

 vated by cuprous oxide or organo-mercurials and reactivated by hydro- 

 gen sulfide and reduced glutathione. Benzoquinone depressed the 

 activity of purified hemolysin in 10 minutes; this was partially regen- 

 erated by hydrogen sulfide. Henry (1939) had found that reduced 

 glutathione given either in vitro or in vivo counteracted the anticoagu- 

 lant activity of cobra venom. Tetsch and Wolff (1937) analyzed 

 various animal and insect toxins and found the following correlation 

 between the sulfur content and toxicity. 



