494 



KINETICS OF TRYPSIN DIGESTION 



therefore, be used to determine the relative rate of digestion of dif- 

 ferent gelatin concentrations provided the change used as end-point 

 is so small that the gelatin concentration can be assumed to remain 

 constant during the course of the experiment. 



TABLE m. 



Time Required to Cause an Equal Change in the Conductivity of 1 and 5 Per Cent 

 Gelatin Solutions with 1 Unit of Trypsin and 10 Units of Trypsin. 



Influence of the Viscosity of the Solution. 



It has been suggested that the anomalous results obtained by 

 increasing the concentration of substrate are due to the increased 

 viscosity of the solution. That this is not the cause of the retarda- 

 tion in the present experiments is shown in Table IV which gives the 

 results of an experiment performed with the same gelatin solution 

 which had been kept at 25°C. for varying lengths of time." The 

 viscosity increases slowly under these conditions. As the table 

 shows, the gelatin digests at the same rate whether it has a viscosity 

 of 2.5 times that of water or of 11 times that of water. The physical 

 properties of the gelatin solution evidently have Httle or no effect on 

 the rate at which it digests. 



Influence of the Substrate Concentration. 



The results of a series of experiments with varying enzyme and 

 gelatin concentrations are given in Table V. The hydrolysis was 

 followed by the change in conductivity and velocity is taken as the 

 reciprocal of the time required to cause an increase of conductivity 



