6 



Scientific Proceedings (117). 



treated by heating (up to 6o° C.) or by means of colloidal iron 

 and other precipitants, the rennet is set free. Now if some of 

 the original extract is added to the activated preparation, no 

 inhibition of the rennet action occurs. In other words, none of 

 the substance which hinders the action of rennet is present in a 

 free state in the pancreatic extract. When alkalinized with 

 ammonia the original extract acquires the power to inhibit the 

 action of active rennet preparations. The result, however, is not 

 due to the setting free of the antagonistic substance (as Hedin 

 believes), but to the fact that the calcium ion, which is essential 

 for coagulation, is rendered inert by the procedure. On the other 

 hand, if a solution of active pancreatic rennet is alkalinized with 

 the hydrate or carbonate of ammonia or soda, the enzyme solu- 

 tion is rendered inactive. If, however, CaCl2 in sufficient amounts 

 is added to this liquor, the rennet is immediately reactivated. 

 Neutralization or alkalinization of the active rennet solution by 

 means of disodic phosphate, or calcium hydrate, does not in- 

 activate the rennet. 



It would appear from this that Hedin's result was not due to 

 inactivation of the rennet by means of the antagonistic substance, 

 but merely to the removal of the calcium ion from the sphere of 

 action. 



The experiments made thus far seem to indicate that the 

 enzyme substance forms a chemical combination with calcium, 

 in the nature of a salt, and only as such exerts its action. There 

 appears to be some ground for the belief that rennet and trypsin 

 reside in a single chemical unit of the pancreatic substance, and 

 possibly represent two phases of one and the same ferment. 



I might add in conclusion that, whereas the evidence is in 

 favor of the view that the rennet in pancreatic substance exists as 

 an active enzyme and not as a pro-rennet, definite proof for this 

 opinion is still lacking. 



