266 



INACTIVATION OF TRYPSEST. Ill 



slowly than demanded by the monomolecular formula. As has been 

 stated this is the experimental result. 



The above explanation may be tested quantitatively as foUows. 

 If the total concentration of trypsin and inhibitor be known the 

 concentration of free trypsin at any dilution may be calculated by 

 the law of mass action, since the equilibrium constant is known from 

 the experiments described in the preceding paper. The constant 



o 

 o 

 o 



& 

 P- 



C 

 o 



■i-' 

 CO 





12 3 



Hours at 38" 



Fig. 2. Inactivation of trypsin in solution containing protein at 38°C. 



for the destruction of the free trypsin is known from the decomposi- 

 tion curve of the purified trypsin. It was found to be about 0.005, 

 using common logs and expressing the time in minutes. That is, 

 very nearly half the amount of trypsin present is destroyed in 1 hour 

 at 38° and a pH of 6.2. If a known amount of inhibitor is added to a 

 known amount of trypsin, therefore, it is possible to calculate con- 

 centration of free trypsin in this solution. Since the value of Kd 

 (the rate of decomposition) is known, the percentage of this free 



