256 



INACTIVATION OF TRYPSIN. II 



enzyme and protein solution used, activity-concentration curves may 

 be found to be either convex or concave or a straight line. This 

 probably accounts for the discrepancies in the literature in regard 

 to this point. If the enzyme solution contained products of protein 

 digestion, as is very likely to be the case, the rate of hydrolysis would 

 not increase as rapidly as the enzyme concentration. If the protein 

 solution was already partially hydrolyzed or contained some inhibiting 

 substance, the velocity of hydrolysis would increase more rapidly 

 than the enzyme concentration. riEfti 



p- 



G 



800 400 200 100 V. 



.031 .052 .125 0.25 



Cc. trypsin solution added to 25 cc gelatin 



Fig. 4. The influence of the presence of inhibitor on the concentration-activity 

 curve of trypsin. Curve A, "pure" trypsin diluted with water. Curve B, 

 mixture of trypsin and inhibitor diluted with water. The ratio of trypsin to 

 inhibitor is therefore constant. Curve C, mixture of trypsin and inhibitor di- 

 luted with a solution of inhibitor of the same concentration as was present in 

 the trypsin solution. The concentration of inhibitor is therefore constant in 

 this experiment. 



Effect of the Hydrogen Ion Concentration. 



In all the foregoing experiments the hydrogen ion concentration 

 was kept constant at a pH of 6.3. It seemed of interest to determine 

 what effect a variation in this factor would have on the retarding 



