ENZYMES AS SYNTHETIC AGENTS 491 



In respect to the difficulties of interpretation, this work is 

 typical of this class of investigation. In the first place there 

 is no certain evidence that the precipitates obtained are com- 

 posed of proteins ; according to some statements they contain 

 too little nitrogen to be classed as protein although they give 

 the reactions of bodies of this class. There is certainly no 

 evidence that they represent the protein bodies from which the 

 peptones were derived by previous hydrolysis, consequently the 

 relation of the reaction to the catalysis of a reversible hydrolysis 

 is not clear. 



This brings us to the second outstanding difficulty, namely 

 that it is not at all clear that the production of these bodies is to 

 be associated in any way with a catalysis of a chemical reaction. 

 Under the existing conditions nothing would seem more pro- 

 bable than a precipitation due to the withdrawal of water from 

 some of the more complex colloids present. The precipitation 

 would in that case be equivalent to the phenomenon of " salting 

 out," and if there were any protein-like bodies present which 

 did not form part of the original precipitate, they would almost 

 certainly be carried out of solution by the precipitate as the 

 result of adsorption. 



In a less degree the same criticism applies to the experiments 

 of Taylor, 1 who in the first place subjected 400 grams of pro- 

 tamin to complete tryptic digestion, and then, converting the 

 products of hydrolysis into carbonates, subjected them to the 

 action of a considerable quantity of tryptase. At the end of five 

 months, about 2 grams of protamin, weighed as sulphate, were 

 recovered from the solution. 



If these experiments are regarded as synthesis under the 

 concentration conditions existing, a certain amount of support is 

 afforded to this point of view by other phenomena. 



In the first place, this is the simplest explanation to give 

 of the retardation of protein hydrolysis produced by the 

 accumulation of the products of hydrolysis. The equilibrium 

 point in a reversible reaction is being approached, and if the 

 products of hydrolysis are present in sufficient quantity a re- 

 versal of the reaction in a synthetic direction may be expected. 

 Secondly, such a reversal of the reaction is the simplest ex- 

 planation of the changes in conductivity of a tryptic digest 



1 A. E. Taylor, Univ. of California Publ. Pathol, i. p. 343 ; and Journ. of 

 Biol. Chem. iii. p. 87. 



