476 



EFFECT OF ENZYME ON DIGESTION OF PROTEINS 



then diluted as shown in the table with HCl while Solution C was di- 

 luted with Solution B in which the pepsin had been inactivated by- 

 making the solution alkaline for 10 minutes. With Solutions A and C 

 the product of the time into the amount of pepsin present is constant 

 as required by the law of mass action, while in Solution B the value 



TABLE IT. 

 Efed of Addition of Peptone to Pepsin Solutions. 

 Solution A. 2.5 cc. of 2 per cent active pepsin diluted to 10 cc. + HCl, pH 2.0. 

 Solution B. 2.5 cc. of 2 per cent active pepsin diluted to 10 cc. + 1 per cent 

 peptone solution, pH 2.0. 



Solutions A and B then diluted as noted + HCl. Pepsin determined in 1 cc. 

 Solution C. Same as B except diluted with inactivated B, instead of HCl. 



of the product decreases with increasing dilution until it becomes 

 equal to that value obtained from Solutions A and B, and then re- 

 mains constant. ^^ The results are plotted in Fig. 2. The straight 

 Hne represents direct proportionality. 



The solutions were made up to contain the same total concentration 

 of pepsin and in the higher dilutions show the same degree of activity. 

 It seems, therefore, that the divergence of Solution B from the regular 

 law must be due to the fact that the peptone combines with the pep- 



"^ This experiment is probably the explanation of the conflicting results ob- 

 tained by Bayliss^ and Nelson and Vosburgh (Nelson, J. M., and Vosburgh, 

 W. C, /. Am. Chem. Soc, 1917, xxxix, 790) in connection with the action of 

 invertase. The activity of the solution of invertase used by Bayliss was not 

 proportional to its concentration whereas the activity of that used by Nelson 

 and Vosburgh was directly proportional. 



