ENZYMES 



167 



Ammonia 



nitrogen 



(mg.) 



Minutes 

 Fig. 31 — Ammonia production during the hydrolysis of urea in the presence of urease. 



A. Influence of Enzyme Concentration 



If we vary the concentration of the enzyme present at the beginning of 

 the reaction and measure the initial reaction velocity for each different 

 concentration, we shall find, in general, that the velocity increases linearly 

 with the concentration of the enzyme : the reaction is therefore first order 

 with respect to the enzyme. 



Units of 

 proteolytic 

 activity 2 



00 cc. 



(volume of solution containing 1ml of trypsin solution.) 



Fig. 32 (Northrop). — Influence of the enzyme concentration on the speed of hydrolysis. 

 Curve A : pure trypsin, proportionality between hydrolysis and tr>'psin concentration. 

 Curve B : ordinary impure enzyme; the speed of hydrolysis is not proportionately increased 



as the enzyme concentration is increased. 



