1913.] 



Studies on Enzyme Action. 



595 



" Different amounts of soya bean oil were hydrolysed by the ' lipase powder ' 

 in the presence of different amounts of fatty acid at 38° 0. The results 

 were as follows : 



Oil 



Acid 



Enzyme 



Water 



Grammes of oil 

 hydrolysed 



Percentage of oil 

 hydrolysed 



1 hour 



2 hours 



1 hour 



2 hours 



giro. 



grm. 



grm. 



grm. 











50 







2 



18 



22 -00 



32 -50 



44-0 



65 -0 



40 



10 



2 



18 



17 -73 



26-33 



44-1 



65 - 5 



30 



20 



2 



18 



13 -13 



20 -31 



43 2 



66 -8 



10 



40 



2 



18 



4-70 



7 33 



43 o 



67 -9 



" These data show that the amount of oil hydrolysed is directly pro- 

 portional to the amount of oil present or the rate of change follows tbe law 

 of mass action, even in the presence of a large amount of free fatty acid. 

 This result proves without doubt that the fatty acid has no retarding effect 

 upon the enzyme action, because, if that were the case, it would lead to a 

 slowing of the reaction greater than that due to the diminished concentration 

 of the neutral oil." 



Tanaka's experiments do not appear to us to justify these conclusions. 

 It will be noticed that the four interacting substances were all present in 

 different relative proportions in each of the four experiments — consequently 

 the results are not comparable. 



It is not to be expected that an oil will behave as an aqueous solution, but 

 there must be some optimum proportion of enzyme to oil beyond which the 

 oil will be in excess, as it is obvious that any influence the products of 

 change can exercise will be relatively greater the smaller the proportion of 

 oil present. 



That the extent to which hydrolysis takes place is not proportional to the 

 amount of oil used is shown by the following results of a series of experi- 

 ments in which 1 grm. of enzyme and 4 c.c. of water were digested during 

 20 hours with varying amounts of oil : — . 



Oil used 

 10 grm. 

 20 „ 

 30 „ 

 50 „ 



No. of c.c. 

 X XaOH neutralised 

 18-6 

 263 

 28-9 

 35-6 



Per cent, of oil 

 hydrolysed 

 54 - 5 

 38-1 

 28-0 

 20-6 



