560 
CHEMISTRY: K. G. FALK 
of proteins, it is evident that such a rearrangement is possible in the 
peptide linking. 
The hypothesis to be suggested is that the active grouping of the 
esterase and lipase preparations is of the enol structure — C(OH) =N — , 
the specific actions being dependent in part upon the groups combined 
with the C and N, and that inactivation consists primarily in a re- 
arrangement to the keto group — CO-NH — . Such structures have 
been proposed at different times as indicating the difference between 
proteins in living matter, and proteins not in living matter. 
Since strong alkali, as a rule, favors the formation of the enol struc- 
ture in such tautomeric changes, a way is open to test the hypothesis. 
Activation of proteins hy alkali. — One gram of inactive solid lipase- 
preparation, washed and dried by means of alcohol, was allowed to 
stand 24 hours with 25 cc. 10% NaOH solution (and toluene). The 
brown suspension or mixture was diluted with 100 cc. water and dia- 
lyzed against running water for 24 hours to remove the greater part 
of the alkali. The volume increased to 410 cc. The mixture was 
brought to a very faint pink color toward phenolphthalein with hydro- 
chloric acid, and the hydrolytic action of 50 cc. portions (corresponding 
to 0.12 g. original material) was tested for 48 hours. An action (cor- 
rected for blanks) of 0.24 cc. was found with ethyl butyrate, and 0.73 
cc. with glyceryl triac tate. 
Many experiments \\ ere also carried out with casein (Kahlbaum's 
preparation *^nach Hammarsten"), of which the following may be cite ' 
Two grams of casein were mixed with 25 cc. 1 normal NaOH solutj 
(and toluene). After 24 hours at room temperature, a grayish-brown 
and dialyzed 48 hours, the volume increasing to 280 cc; the H+ ion 
concentration was then brought to 10~^-^, and the hydrolytic actions of 
40 cc. portions, corresponding to 0.3 g. of casein each, were tested for 
48 hours. The actions found were 0.08 cc. with ethyl butyrate and 
0.48 cc. with glyceryl triacetate. A large number of similar experi- 
ments were carried out in which the alkali was removed either by 
dialysis alone or by direct neutralization with acid. There was marked 
action on glyceryl triacetate, but only very slight action on ethyl 
butyrate. 
The strength of the alkah, between 0.1 normal and 3 normal, used in 
the preliminary treatment, appeared to have small influence on the 
activity produced; but great influence was exerted by the H+ion con- 
centration of the solutions in the activity tests. This last effect may 
be shown by a series of results with 1 normal NaOH solution in which 
