466 



INACTIVATION OF PEPSIN SOLUTIONS 



In the experiments considered in this paper the effect of the fol- 

 lowing variables on the inactivation of pepsin in solution has been 

 studied: (1) the hydrogen ion concentration; (2) the anion of the acid; 

 and (3) the purity of the enzyme solution. 



The results of the experiments are given in Tables I and II and in 

 Figs. 1 and 2. The figures in the tables are the relative amounts of 

 active enzyme present in the solution after 24 or 48 hours. The 

 total active enzyme present at the beginning of the experiment 

 is taken as 10 units. The time required to cause a constant change 



TABLE I. 



Influence of the Purity of the Enzyme Solution on the Destruction of Pepsin at 

 Various Hydrogen Ion Concentrations. 



o 

 u 





pH 6 



Fig. 1. Relative amount of active pepsin at dififerent hydrogen ion concen- 

 trations with various acids after 24 hours at 38°C. 



