482 



EFFECT OF ENZYME ON DIGESTION OF PROTEINS 



tone originally present, were taken from Table I. The value for E 

 in Solution B was determined by a separate experiment. It will be 

 seen that the total amount of active pepsin found in the solution is 

 not equal to the sum of the amount of active pepsin added plus the 

 amount of active pepsin already present. This shows that the pepsin 



TABLE IV. 

 Addition of Active Pepsin Solution to Solution of Griibler's Pepsin. 

 Solution A. 10 per cent Griibler's pepsin, pH 2.0. 

 Solution B. 3 per cent active pepsin, E =4.2. 



K = 7.2, d = 3.0, E (in Solution A) = 2.69 (Table I). 1 cc. of Solution A + 

 noted cc. of B made up to 10 cc. K = 7.2. 



is in equilibrium with the substance that inhibits its action. The 

 fact that the calculated values agree with those found by experiment 

 shows that the equilibrium obeys the law of mass action since the 

 calculated figures are obtained by means of this law. 



The Effect of Inactivated Pepsin on the Equilibrium. 



The results of Experiment 2 show that if a solution of pepsin (A) 

 containing peptone is diluted with acid, the activity of the resulting 

 solution is not directly proportional to the concentration of A. If the 

 same solution is diluted with a portion of itself in which the pepsin 

 has been inactivated with alkali, the activity of the resulting solution 

 is directly proportional to the concentration of A. This is the result 

 predicted if it is assumed that the inactive pepsin enters into the 

 equilibrium {i.e. combines with the peptone) to the same extent as 



