1913.] 



Studies on Enzyme Action. 



599 



But the activity of the enzyme seems also to deteriorate during its action 

 on oil, as the following results show : — 



Oil hydrolysed 

 Grammes 



5 grm. of oil + 2 c.c. of water + - 5 grm. of lipase powder digested a. 3'50 

 during 5 days at 30° C. b. 3'49 



As in a and b but after 48 hours' digestion 5 grm. of oil + 2 c.c. of c. 3'66 

 water were added and the digestion extended to 5 days d. 3"88 



Evidently the enzyme had been to a large extent destroyed during the 

 first period of digestion in experiments c and d. 



In view of the possibility that the enzyme does not deteriorate when used 

 to hydrolyse succinic ether in the way that it does when used with a fatty 

 material might be due to the fact that the acid liberated, in the former case, 

 is much stronger than the higher fatty acid and therefore serves to preserve 

 the lipase from destruction by inhibiting the action of proteoclastic enzymes, 

 a second similar series of experiments was made, using 10 c.c. of water in 

 the one set and 10 c.c. of N/10 succinic acid in the other. Practically the 

 same results were obtained with oil and water alone as before but only about 

 one-third as much oil was hydrolysed in presence of the acid and there was 

 no increase after adding the second portion of oil. 



What has been said in this section will serve to show that the difficulties 

 attending the study of the action of lipase on fats are considerable. We 

 may here point out that we are inclined to attribute the observed inferiority 

 of liver lipase as a hydrolyst of fats to the unnatural conditions under which 

 it is applied when the material used is the expressed juice from an animal 

 organ. Under natural conditions the lipase and fat are in close conjunction, 

 not suspended in water. 



When the graphs given in the diagram on p. 597 are inspected, it is obvious 

 that at first the action proceeds at a rapid rate. Therefore, taking into 

 account the influence of the products of change and the fact that the enzyme 

 diminishes in activity during use, it is not improbable that far from being in 

 accordance with the law of mass action, the change proper proceeds in the 

 manner which appears to be characteristic of other enzymes — i.e. the graphs 

 representing the rate of change would be nearly linear, if the disturbing 

 influences could be allowed for. 



As to the nature of the enzyme, it is difficult to formulate any definite 

 conception but we are inclined to extend the argument advanced in the 

 previous communication and to take the view that, as already suggested, 

 the configuration of lipase is such as to favour its association with glycerides 

 of the higher fatty acids — in other words, that it contains a glyceric nucleus 



VOL. LXXXVI. — B. 2 Y 



