CHEMISTRY: K. G. FALK 
139 
converting inactive material present in the bean into active enzyme. 
For it was found that when an original castor-bean preparation has been 
made inactive by heating its solution, it can be partially reactivated by 
adding manganous salt and passing a stream of air through the solution. 
The active substance is also produced by placing a solution or sus- 
pension in contact with an anode and submitting it to a long-continued 
electrolysis. These facts evidently support the explanation of the forma- 
tion of active enzyme from inactive material by oxidation ; but hydroly- 
sis is perhaps also a factor. 
The cycle dead, living, dead, occurs here in perhaps one of its simplest 
manifestations, exemplified by the transpositions inactive material of the 
bean, active enzyme, inactive or 'killed' enzyme material. The possi- 
bility of such a regenerative action occurring in the growth and develop- 
ment of the castor bean led to testing the oil-free kernel for manganese. 
A definite test for it was obtained; and the amount present was esti- 
mated to be 0.0006% of the oil-free kernel, or 0.008%of its ash. 
Efect of Alcohols and Esters on the Rate of Hydrolysis Caused by Lipases. 
Methyl and ethyl alcohols were found to exert retarding effects on the 
rate of hydrolysis — effects which continuously increased with increasing 
concentration of the alcohols. Methyl alcohol retarded the hydrolyses 
somewhat more than did ethyl alcohol. Glycerin, on the other hand, had 
no effect even at a concentration of 25%. The retardation was shown 
to be due to coagulation of the enzyme. 
Since the simple esters are similar in physical properties to the simple 
alcohols, it was thought probable that they would exert similar coagu- 
lating or inactivating actions on the active enzyme. Methyl acetate 
should then exert greater retarding action on the enzyme than ethyl 
acetate, while with glyceryl triacetate, the retardation might well be 
negligible. Similarly, esters containing the lower acid radicals, such as 
ethyl acetate, might be expected to exert retarding effects; while esters 
containing the higher radicals such as ethyl butyrate, might have consid- 
erably less effect. These hypotheses were tested, and were found to be 
confirmed. From these results the glycerides of the higher fatty acids 
which occur in nature would be expected to exert no inhibiting action 
on the lipase materials. 
These actions of the esters on the lipases serve to explain part of the 
selective actions of the lipases which have been described in the past. 
They make it evident that the action of the substrate (substance acted 
upon) on the enzyme must in all cases be taken into account when con- 
sidering reactions of enzymes. 
