558 
CHEMISTRY: K. G. FALK 
appeared to offer the most promising field for further study; a prelimi- 
nary report on the results of this study is here presented. 
The materials used were Esterase preparation, a clear, dialyzed and 
filtered water-extract of oil-free and husk-free castor beans 0.5 g. to 
60 cc; and lipase preparation, a mixture from the 1.5 normal NaCl 
solution extract of water-extracted castor beans, 1.0 g. to 100 cc, 
dialyzed until salt-free. The former, a clear colorless solution, was 
more suitable for following the changes under different conditions than 
the latter, which was a suspension of globulin in water. 
The activity tests were carried out with 1 cc. ethyl butyrate or 0.5 
cc. glyceryl triacetate at 38° for 24 or 48 hours, and the results given 
as the number of cubic centimeters of 0.1 normal alkali required for 
neutralyzing the acid produced with phenolphthalein as indicator, with 
suitable corrections for blanks. 
Inactivation of the enzymes by acid. — The hydrogen-ion concentra- 
tions were determined by color comparison with the standard solutions 
and indicators recommended by A. A. Noyes.^ The esterase prepara- 
tion, H+ = 10~'^ '', brought to H+=10-^-^ with acetic acid for 24 hours 
and then back to H+ = lO-^ o, lost its activity completely. At H+ = 10-^-^ 
under the same conditions for the same length of time, one-third of 
the activity was lost, while at H+=10~^-o about one-eighth was lost. 
The difficulty of color comparison with the lipase preparation made 
difficult an exact determination of the H+ ion concentration at which 
inactivation took place. A larger H+ ion concentration than with the 
esterase preparation appeared to be necessary to produce a correspond- 
ing effect. 
Inactivation by alkali. — The esterase preparation lost one-eighth of 
its activity after being kept at H+ = 10~^-^ for 24 hours, and became 
practically inactive at H+=10-io-^ and lO-^i-^ The lipase prepara- 
tion dissolved to form a cloudy solution at H+ = 10~^i '^. Kept at this 
for 18 hours and then brought back to H+=10~^-o, one-half of the ac- 
tivity was lost. At about H+ = 10-i2^ one-third of the activity re- 
mained, and at about H+ = 2XlO~i2^ one-sixth remained. 
Inactivation by alcohols and by acetone. — It was shown previously 
that dilute solutions of methyl alcohol, ethyl alcohol, and acetone 
inhibited the action of both preparations. Solid preparations made by 
precipitation and washing with alcohol were always inactive. Solid 
esterase preparations, precipitated and washed with acetone, were 
active in a number of cases; but the activity was much smaller than 
that of the corresponding solutions from which they were prepared. 
Similar solid lipase preparations were always inactive. 
