ENZYMES AS SYNTHETIC AGENTS 495 



explanation of observed phenomena until investigation shall 

 establish beyond a doubt that the simple explanation, such as 

 that an enzyme as a catalyst obeys the physico-chemical laws 

 governing the definition of a catalyst, will no longer cover the 

 whole of the ascertained phenomena. 



It is therefore considered premature for the same reason to 

 discuss Euler's l suggestions as to anti-enzymes being active in 

 synthesis. It is not yet clear that simpler explanations will not 

 suffice. 



Euler points out that various investigators have found that 

 the result of subcutaneous injection of enzymes into the animal 

 organism is the production of specific anti-bodies. These 

 bodies, termed in some cases anti-enzymes, have been reported 

 to exhibit catalytic activity, and it is suggested that they act in 

 the direction of synthesis and not of hydrolysis. 



It is quite possible that this hypothesis may ultimately prove 

 of value, but it is at present unnecessary for the explanation of 

 the observed reversal of enzyme action. It is also perhaps 

 worth pointing out that the terminology adopted is a little 

 unfortunate, because the term anti-enzyme has often been used 

 in reference to specific cases, and the implication has been that 

 the anti-enzyme concerned produced its inhibiting effect directly 

 upon another enzyme, 2 and not necessarily by accelerating a 

 reaction against its normal equilibrium conditions. Further- 

 more, such bodies as Euler refers to should surely have no claim 

 at all to the name of enzyme. An enzyme has been generally 

 regarded as an organic catalyst, and these bodies cannot be 

 regarded as, in any sense of the word, chemical catalysts. They 

 seem to act in defiance of the laws of mass action. 



Finally, in considering the various aspects of the subject 

 reviewed in this paper, the writer would emphasise the fact 

 that there is no pretence of giving more than partial glimpses 

 of a very extensive problem. Both in relation to carbohydrate 

 and protein metabolism, the physiologist anxious for guidance 

 in his attempt to outline experimentally the highways of 

 metabolic activity in the organism is bewildered by the variety 

 of hypothesis permitted him by the fruitful discoveries of 



1 Euler, loc. cit. p. 267 (Eng. ed.). 



s See, for instance, Czapek upon anti-oxidase, Ann. of Botany, or the use of 

 the term anti-glyoxalose by Dakin and Dudley, Journ. of Biol. Chem. xiv. p. 463. 



