The Activation of Pancreatic Extract. 131 



In another experiment fresh dog's pancreas was inactivated by 

 treatment with 0.2 per cent, sodium hydrate as above. The sodium 

 hydrate was neutralized, and an attempt made to activate the alkali- 

 treated pancreas with various agents. The inactive pancreas was 

 allowed to stand for twenty-four hours at 37 0 C. in contact with 

 the substances used for activation, and proteolysis was subsequently 

 tested in acid, neutral and alkaline medium. The quantities of 

 pancreas used and the technic were the same as in the experiment 

 described above. 



Activation of Pancreas Inactivated by Treatment with 0.2 per cent. Sodium Hydrate, 



Medium. 



Substances used for activation. 



Heated 



0 



Enterokinase. 



0.2 56 acet. ac. 



Active pancreas. 



pancreas. 



0.2 % acetic 

 acid 



0.5 c.c. 



8.8 c.c. 



1.2 C.C. 



0.0 C.C. 



0.8 C.C. 



Neutral 



0.5 c.c. 



19.0 c.c. 



2.6 c.c. 



0.9 C.C. 



2 3 C.C. 



0.2 % sodium 

 carbonate 



0.6 c.c. 



21.5 c.c. 



0.9 c.c. 



O.I C.C. 



0.8 c.c. 



From this experiment it is observed that pretreatment of fresh 

 pancreas with 0.2 per cent, sodium hydrate completely prevents 

 subsequent proteolysis. The enzyme of alkali-treated pancreas is, 

 however, not destroyed inasmuch as it can subsequently be acti- 

 vated by the addition of enterokinase. Acetic acid (0.2 per cent.) 

 which readily activates fresh pancreas is not able to effect to any 

 appreciable extent activation of pancreas treated with alkali. Ac- 

 tive pancreatic extract, Vernon's most effective agent for activating 

 inactive pancreatic extract develops no activity in alkali-treated 

 pancreas. 



From these results it would seem that the activating effect of 

 acid and the inactivating influence of alkali upon fresh pancreas 

 do not represent a direct action upon the proteolytic zymogen, 

 but probably exert their influence through the destruction of sec- 

 ondary substances which are necessary for the preservation of 

 enzymotic equilibrium. The suggestion is made that the enzyme 

 complex upon coming in contact with the alkaline reaction 

 of the pancreatic juice undergoes a change analogous to that ob- 

 served in the treatment of fresh pancreas with alkali, so that it is 

 no longer readily activated by any agent other than the enteroki- 

 nase of succus entericus. 



