REVERSION OF HYDROLYSIS 427 



reaction (B) . In the absence of any catalysors this reaction takes 

 place very slowly, but if any of the catalysors be present which 

 are capable of accelerating the hydrolysis of maltose, for example 

 maltase, then the synthesis of maltose or of isomaltose occurs 

 with measurable rapidity. It was by adding maltase to con- 

 centrated glucose that Croft Hill obtained a fermentative synthesis 

 of isomaltose. 



In satisfactory accord with the above account of the chemical 

 mechanics of fermentative reversions, the majority of observers 

 have found that reversion of a fermentative hydrolysis is only 

 attainable when the enzjone is made to act upon the concentrated 

 products of the hydrolysis. Nevertheless reversion does not 

 always occur when it might be expected to occur; thus Bradley 

 (9) has shown that in the presence of 50 per cent of water no 

 appreciable synthesis of triolein from glycerin and oleic acid 

 can be brought about through the agency of lipase, although 

 in the presence of 50 per cent of water an appreciable proportion 

 of triolein remains unhydrolysed. The converse is also true, 

 reversion occurs when it might not be anticipated. Thus I find 

 (53) that it is possible to completely hydrolyse paranuclein to 

 products which have lost its characteristic properties and yet, 

 without any previous concentration, to bring about, through 

 simply altering the temperature and the enzyme concentration, 

 a fermentative synthesis of this substance. These apparent 

 anomalies arise from the fact that these ferments do not belong 

 to that restricted class of catalysors which, as explained in sec- 

 tion 1 of the previous chapter, has come to be regarded as typical, 

 but to what Stieglitz has shown to be the more general class of 

 catalysors, namely those which appreciably participate in the 

 reactions which they accelerate and therefore appreciably disturb 

 the final equilibrium. The significance of these phenomena, in so 

 far as the proteolytic enzymes are concerned, will be more 

 fully discussed below. 



The fermentative synthesis of protamin through the action 

 of trypsin upon the concentrated products of its hydrolysis has 

 been accomplished by Taylor (69) (70) and I have described the 

 fermentative synthesis of paranuclein (51) (52) through the 

 action of pepsin upon the products of its hydrolysis. 



In Taylor's experiments the mixed products of the tryptic 

 digestion of protamin sulphate were converted into carbonates 



