1921] 
KARRER—H-ION CONCENTRATION AND AMYLASE ACTION 67 
Michaelis, publishing with Davidson and later with Peck- 
stein, established definite H-ion concentration optima for various 
enzymes and also showed that there is an optimum zone rather 
than a sharply defined point. Michaelis and Peckstein found 
that ptyalin formed complex combinations with many neutral 
salts. The affinity for various anions varied greatly, being 
greatest with the nitrate ion, slightly less with chlorine and 
bromine, and very little with the sulphate, acetate, and phos- 
phate ions. Each one of these diastase-complexes was found 
to be a characteristic compound, the fermentative action upon 
starch being noticeably different and the H-ion concentration 
optima with regard to activity also varying. The chlorine 
complex produced the most reactive combination, the nitrate 
slightly less, and the sulphate, acetate, and phosphate least of 
all. The H-ion concentrations producing optimum activity 
were found to be as follows: 
Nitrate-diastase .. .. ci ora 22 9228 2 P46.9 
Chlorine-diastase........ 22525 2359 Px6.7 
Phosphate-diastase 
Sulphate-diastase (.............. P46.1-6.2 
Acetate-diastase 
A series of investigations carried on by Sherman and his 
associates has been helpful in indicating a field for the study of 
the properties and conditions for the action of amylases when 
purified materials are used. 
Sherman and Thomas (’15) determined the H-ion concen- 
tration most favorable for the activity of malt amylase at 40* 
C. The weak and strong acids and the acid phosphates of 
sodium and potassium all showed an optimum activation in 
solutions having nearly the same actual acidity, this varying 
from Py 4.2 to 4.6. With amounts of strong acid above the 
optimum concentration, the depression of action was greater 
than with corresponding excesses of weak acids. The activity 
was determined by the reduction of Fehling’s solution and also 
by the starch iodide method as in Wohlgemuth's modification. 
The results with these two methods were found to differ. The 
amyloclastie action, as measured by the Wohlgemuth method, 
reached an optimum at a concentration of the activating agent 
(either salt or acid) much below that which gave optimum 
