260 INACTIVATION OF TRYPSIN. II 



hydrolysis is proportional to the concentration of the free tr3^sin and 

 that the equilibrium conforms to the law of mass action, it is possible 

 to calculate the experimental results by the application of the law of 

 mass action. 



4. The equilibrium has been studied by varying (a) the concentra- 

 tion of the inhibiting substance, (b) the concentration of trypsin, (c) 

 the concentration of gelatin, and (d) the concentration of trypsin and 

 inhibitor (the relative concentration of the two remaining the same). 

 In all cases the results agree quantitatively with those predicted by 

 the law of mass action. 



5. It was found that the percentage retarding effect of the inhibiting 

 substance on the rate of hydrolysis is independent of the hydrogen 

 ion concentration between pH 6.3 and 10.0. 



6. The fact that the experimental results agree with the mechanism 

 outlined under 3, is contrary to the assumption that any appreciable 

 amount of trypsin is combined with the gelatin at any one time; i.e., 

 the velocity of the hydrolysis must depend on the time required for 

 such a compound to form rather than for it to decompose. 



7. The experiments may be considered as experimental proof of 

 the validity of Arrhenius' explanation of Schiitz's rule as applied to 

 trypsin digestion. 



8. Inactivated trypsin does not enter into the equilibrium. 



Many of the experiments described in this paper were carried out 

 by Mr. Frank Johnston. 



