CHEMISTRY: K. G. FALK 
137 
This investigation on the action of lipases was therefore undertaken. 
It has now been in progress for a number of years; and a series of papers 
describing the experiments in detail have been pubushed in the Journal 
of the American Chemical Society for the years 1912, 1913, and 1914. It 
is the purpose of this paper to summarize the more important results 
and conclusions. With reference to these it should be stated that the 
aim of this investigation has been, not so much to follow the changes 
which the lipase produces in other substances (for example, by measuring 
the rate at which it causes the hydrolysis of different esters), as to study 
the changes in the activity of the Kpase itself under various conditions, 
in the hope of obtaining information with regard to the chemical and 
physical properties of the substance or substances upon which the lip- 
olytic actions depend. 
Preparatio7i of Extracts Containing Two Kinds of Lipase from Castor 
Beans. Lipases were prepared from both vegetable and animal sources. 
The most satisfactory and interesting material was found to be husk-free 
and oil-free castor beans. From these beans two distinct kinds of en- 
zyme were readily extracted and separated from each other. These two 
preparations differed from each other in their hydrolytic action upon 
esters. Under certain fixed conditions the one was found to exert a 
comparatively greater action on ethyl butyrate than on glyceryl triace- 
tate; the other to exert a comparatively greater action on glyceryl tri- 
acetate than on ethyl butyrate. The two kinds will be called esterase 
and lipase, respectively. Ethyl butyrate was used in these hydrolysis 
experiments as an example of a simple ester not readily hydrolyzed by 
water; glyceryl triacetate, as an example of an ester analogous to the 
naturally occurring fats and oils, from which it differs, however, by its 
greater solubility in water which makes it more convenient in compara- 
tive experimental work. 
The esterase of castor beans was found to be associated with sub- 
stances soluble in water; for clear aqueous solutions of it are obtained by 
direct extraction with water, dialysis, and filtration. The lipase of cas- 
tor beans was obtained by extracting the water-insoluble castor-bean 
preparation with 1.5 normal sodium chloride solution, in which it shows 
a maximum solubility, and removing the salt by dialysis. In this way 
a mixture containing the lipase in suspension is formed. 
There was no indication of the presence of a co-enzyme with either 
the esterase or hpase. The identity of the esterase with glycerophos- 
phatase described by Plimmer (Biochem. J., 7, 43; 1913) was made 
probable. 
