1921] 
KARRER—H-ION CONCENTRATION AND AMYLASE ACTION 69 
A study of the activity of a purified malt amylase in buffered 
solutions of varying H-ion concentrations was also made by 
Adler (16). The enzyme was allowed to act upon the sub- 
strate for one hour at 20? C. and the activity measured by the 
reduction of Fehling's solution and also by the starch iodide 
reaction. As a result of these investigations, he found that 
there was an optimum point of Pa 4.9 and that an increase or 
decrease in the H-ion concentration resulted in a rapid suppress- 
ion of action. It was also shown that neutral ions were not 
without effect, although they exerted an influence less than the 
Hions. Determinations with polarized light of the reducing 
substances in the solutions gave unsatisfactory results, since 
the solutions were not always clear. Adler believed that a 
direct relation between the reduction of Fehling’s solution and 
the amount of polarization did not always exist, thus indicating 
the possibility of a difference in the effect of the H-ion concen- 
tration upon the dextrin production. 
In this connection, the work of Chrzaszez and Joscht ('17) 
may be mentioned. They concluded that malt amylase was 
composed of two clearly defined enzymes, a starch-dissolving 
enzyme, a sugar-producing enzyme, and a starch-dextrin en- 
zyme, which was considered a resultant of the two foregoing 
enzymes. The iodine reaction corresponded first to the activity 
of the starch-dissolving and then to the sugar-producing enzyme. 
However, the correspondence was mostly to the soluble portion. 
The hydroxides, in general, were found to be unfavorable to 
the production of sugar in the enzymic reaction, but favorable 
to the starch-dissolving and dextrin-forming complexes. 
Using a modified Lintner method, Falk, McGuire, and Blount 
(19) studied some vegetable enzymes in fresh, vacuum-dried 
and air-dried material in relation to acidity, at 37? C., acting 
for 2 hours. Well-defined optima were obtained at about Py 6 
with eabbage, carrot, and white turnip juices. With yellow 
turnip juice, the optimum action extended from Py 4 to 7. The 
H-ion concentrations of all the juices from fresh and dehydrated 
material prepared according to the method described were found 
to be about Py 6. Thus, it is seen that the optimum H-ion 
concentration for the amylases coincided with the natural H-ion 
concentration of the juices. Dehydration decreased the action in 
every case. 
