CATALASE REACTION OF MILK. 325 
the previous solution through parchment paper, and gave 
no reaction for proteins. Since this solution does not con- 
tain proteins the use of mercuric chloride is not necessary. 
If the decomposition of hydrogen peroxide by catalase 
proceeds as a typical first order reaction any increase in 
the concentration of the hydrogen peroxide should have no 
efiect on the velocity constant. As will be seen from the 
figures in Table VI, the rate at which the reaction proceeds 
gradually diminishes with increase in hydrogen peroxide 
concentration, showing clearly that the hydrogen peroxide 
must have an inhibiting influence on the action of the 
enzyme. 
Table VI. 
Temperature 25° C. 
Concentration of Concentration of he LoS at as 
enzyme. hydrogen peroxide. Het py Rex / Conc. He0g 
l M /500 53 DAs 
] M/160 4) 3°4 
] M/120 36 3°3 
l M/80 31 3:5 
The values of X are calculated on the assumption that 
the reaction goes to anend. From the figures in the last 
column of the above table it will readily be seen that the 
inhibiting action of the hydrogen peroxide for the higher 
concentrations is proportional to the square root of the 
concentration of hydrogen peroxide. The rate at which 
the inhibiting action proceeds will be considered at a later 
‘stage. 
Effect of temperature on the velocity constant. 
As is the case with all catalytic actions, increase of 
temperature increases the velocity of the reaction. Inthe 
following table are given the temperatures at which the 
reaction took place and the value for the velocity constants 
K and K, at that temperature. The enzyme solution was 
