254 Optimum Temperature of Salicin Hydrolysis, etc. 



the optimum temperature determined in actions of 15 hours' duration with 

 quantities of the enzymic specimen giving concentrations varying between 

 1/8 x 10 -5 and 18 x 10 -5 grm. per cm. 3 . The numbers obtained are given in 

 Table VI. The results are recorded graphically in fig. 10. 



The curves of fig. 10, as well as the M/30 curve of fig. 4 and that of fig. 8, 

 show that the optimum temperature of the enzyme is the same in each, and, 

 consequently, independent of the concentration of the enzyme. This holds 

 true, as shown by two of the curves in fig. 10, even when the proportion 

 of enzyme to substrate is more than sufficient to produce complete hydrolysis 

 of the substrate at the optimum point. Here the optimum point is imaginary, 

 and corresponds to the intersection of the curves representing respectively 

 the activation and the destruction of the enzyme by heat. 



Briefly, then, the outcome of the inquiry is, for an action of known duration, 

 the optimum temperature of the enzyme investigated is independent alike of 

 the concentration of the substrate and of the concentration of the enzyme. 

 Whether the statement be true of enzymes in general — as theoretical con- 

 siderations would lead one to expect — I propose to answer by fresh experiments 

 on other types of enzymes. 



100 



10 20 30 40 50 60°C 

 temperature ► 



/Substrate cone 1 ? M/30. 

 1 Ervjyme cones |-8xlO~ J to ISxIOgrpercrn 3 



