600 



Studies on Enzyme Action. 



attached to a carboxylic centre in proximity to an acidic group which can 

 determine the hydrolysis of a fatty molecule which becomes attached to the 

 glyceric nucleus. It is conceivable that a single carboxylic centre in con- 

 junction with the glyceric nucleus would be sufficient to constitute an 

 acceptor of fats; this would allow of the attachment of the glyceric nucleus 

 to a colloid complex and leave the third carbon atom free to combine in some 

 other way : if a phosphoric residue became associated with this carbon atom, 

 it would probably serve as agent. Such an assumption is in accordance with 

 the instability of the enzyme, it may be added. 



Summary. 



Following directions given by Yoshio Tanaka, a method is described of 

 rendering the lipoclastic enzyme in castor oil seed active by treatment with 

 dilute acid — preferably acetic acid. 



It is suggested that the " zymogen " is merely a salt. 



Much evidence is quoted showing that the activity of the acid treated 

 enzyme is interfered with even by dilute acids and that it is easily rendered 

 inert, by excess of acid. 



It is contended that lipase is specially fitted to hydrolyse the oily glycerides 

 of the higher fatty acids and is not suited to act in aqueous solutions. The 

 interaction must be supposed to take place at and between surfaces separated 

 only by a thin film of water at most. 



It is shown that the products of change, both the fatty acid and the glycerol, 

 especially the former, inhibit the interaction of enzyme and oil. 



As the rate at which interaction takes place is dependent presumably on 

 the conditions at the colloid surface and these cannot be expressed in terms 

 of the concentration of the solution, it is impossible to apply the law of mass 

 action to the interpretation of the changes observed. Probably, as in other 

 cases of enzymic action, a given amount of enzyme changes equal amounts 

 of material in successive equal intervals of time, the observed departure 

 from this rate being due to the inhibiting effects of the products of change 

 and also to the destruction of the enzyme. 



