1913.] 



Studies on Enzyme Action. 



587 



equivalent quantities, although when used in sufficient amount the weak 

 were as effective as the strong, it appeared to be probable that the strength 

 of the acid was a factor in the action. 



The enzyme could not be separated from the seed. An attempt that was 

 made to liberate it by treating the residue left after extracting the seed with 

 sulphuric acid and removing the excess of acid by washing thoroughly was 

 unsuccessful : apparently the enzyme was destroyed. 



The final conclusion arrived at was that the Ricinus enzyme is possessed 

 of properties which make it specially capable of promoting the hydrolysis 

 of glycerides of the higher fatty acids. 



In the second communication, results were quoted which again were an 

 indication that the strength of the acid used in promoting the hydrolysis 

 of fats was a factor of importance and that, in the case of the stronger 

 acids used, no action took place when more than a certain proportion of acid 

 was present. 



The conclusion of chief importance arrived at in this communication was 

 that comparable results could only be obtained, in the case of ethereal 

 salts soluble in water, by using solutions of equivalent concentration : from 

 which it follows that no comparison can well be made between soluble and 

 insoluble ethereal salts. 



When soluble salts were compared, it was found that the enzyme was the 

 more active the less soluble the ethereal salt and the weaker the acid from 

 which the salt was derived. Thus ethylic succinate was hydrolysed to a 

 considerable extent and the far more soluble allied ethylic tartrate 

 (dihydroxysuccinate) was scarcely if at all affected,* the salt of intermediate 

 solubility, ethylic malate (monhydroxysuccinate), being acted upon less 

 readily than the succinate but more readily than the tartrate. 



In explanation of these results, it was suggested that the attachment of the 

 enzyme to the carboxylic centre of the ethereal salt — the necessary first 

 act in the process of hydrolysis — was interfered with by the hydration of 

 this centre, the implication being that hydration took place the more readily 

 and to a greater extent the more soluble the ethereal salt. 



Various results were quoted in this communication showing that, whilst it 

 was less active towards fats than Ricimis lipase, liver lipase determined the 

 hydrolysis of various ethereal salts without any addition of acid : though 

 attention was not directed specially to this point, on this account and because 

 of the retardation of hydrolysis by acids when used in excess, the opinion had 



* We are inclined to think that the slight amount of action observed in this case is 

 due to the fact that the acid liberated by the direct action of water on the tartrate 

 prevents hydrolysis by the enzyme. 



