INFLUENCE OF TEMPERATURE 419 



split by rennet into two equal parts. The correctness of this 

 interpretation has been completely confii-med by Bosworth (12) 

 who has shown that in the first place no substance other than 

 paracasein results from the action of rennet upon casein, while, 

 in the second place, no matter what proteolytic enzyme (rennet 

 or trypsin) be employed to split the casein, the first step in 

 hydrolysis is the production of paracasein (13). 



As regards the kinetics of the action of fibrin-ferment (throm* 

 bin) Fuld (33) finds that the Schiitz rule (velocity proportional 

 to the square root of the ferment-mass) very nearly holds good, 

 the actual relation between the velocity (v) of coagulation and 

 the mass of fibrin-ferment (E) being: 



V, ^ (E,V 

 V2 Uv 



C. J. Martin finds that for the coagulation of blood by tlirom- 

 hinF X t = constant (78). 



Fibrin-ferment undergoes marked exhaustion during the 

 process of coagulation (84) (60). 



7. The Influence of Temperature upon the Velocity of Protein 

 Hydrolysis. — The influence of temperature upon the hydrolysis 

 of gelatin by trypsin has been carefully studied by Madsen and 

 Walbaum (cited after Arrhenius (3)). The results are in good 

 agreement with the formula: 



Hi = q2\ T,To ), 



Vq 



where e is the base of the Napierian logarithms, Vi and Vo are the 

 velDcities corresponding to absolute temperatures Ti and To and 

 /i is a constant, in this instance 10,570. This is the law which 

 is characteristic of the influence of temperature upon other 

 chemical reactions, and its possible significance, when it is found 

 applicable to protein systems, has been commented upon in 

 Chap. VII. 



The influence of temperature upon the rate of digestion of 

 thymol-gelatin by pepsin is also capable of representation by the 

 above formula (Arrhenius, loc. cit., p. 71). In this case fi = 10,750. 

 The velocity both of pepsin and trypsin-digestion is, therefore, 

 doubled by a rise in temperature from 20 to 30 degrees. 



Using different substrates it is found that, as might be expected, 



