CHEMISTRY: K. G. FALK 
141 
rations in a vacuum desiccator over phosphorus pentoxide was not ac- 
companied by loss in activity; but the same loss in weight by heating at 
100-110° was accompanied by a loss in activity of from 50-80%. By 
drying first and then heating, which caused only a 0.1-0.2% greater loss 
in weight, the same loss in activity was produced. The loss of activity 
of the esterase-preparation caused by salts is due to coagulation or pre- 
cipitation; that of the lipase-preparation caused by treatment with ace- 
tone is apparently due to dehydration. Hydrolysis of the enzyme may 
also play a part under some conditions. 
Relation between the Hydrolytic Effects of Lipases and Those of Proteins 
and Amino- Acids. The hydrolytic actions of lipases are intimately con- 
nected with protein material. If these actions are due to proteins, it is 
probable that only part of the complex protein molecule is directly re- 
sponsible for them. This possibility was studied by measuring the effects 
of some aminoacids and peptides in causing the hydrolysis of a number 
of esters. Some of the results, obtained in part by Dr. M. L. Hamlin, 
are as follows: Glycine, glutamic acid, and aspartic acid exerted hy- 
drolytic actions on methyl acetate, ethyl acetate, glyceryl triacetate, 
phenyl acetate, ethyl butyrate, ethyl benzoate, and phenyl benzoate. 
If these esters be arranged in the order of decreasing amounts of 
hydrolysis, the order is different in the three cases where the action 
is caused by water, by glycine alone, and by glutamic or aspartic acids. 
A comparison of the hydrolytic actions of glycine, alanine, and phenyl- 
alanine on the seven esters also indicated certain selective actions. The 
hydrolysis of methyl acetate and ethyl butyrate by solutions of glycine 
and acetic acid is less than that by corresponding solutions of acetic 
add alone. The hydrolysis of these esters by gly cine-hydrochloric acid 
mixtures was not even approximately proportional to the hydrogen-ion 
concentrations of the solutions. The dipep tides exerted a compara- 
tively greater action on ethyl butyrate than on methyl acetate, while 
the dibasic aminoacids showed the reverse actions. 
The fact that the different esters are hydrolyzed by aminoacids and 
peptides is not in itself surprising. In its bearing on the enzyme work 
its interest lies especially in the selective or specific character of some of 
the actions, which are apparently independent of the hydrogen-ion con- 
centrations, but dependent upon the structure of the aminoacid or pep- 
tide. These effects were, to be sure, small, and the specific character 
of them was not very pronounced; but the possibility of reproducing such 
selective actions even in a small degree with simple groupings which 
themselves may occur in proteins, supports the view that more complex 
