Page 29 - Enzymes in Tropical Soils

Enzymes in Tropical Soils 17

The rate of a biochemical reaction is also determined by the concentration
of enzyme. The increase in enzyme concentration enhances the rate of a
biochemical reaction. However, the increase in the reaction rate is also dependent
on the concentration of substrate. The highest reaction rate occurs when the
concentration of substrate is above maximum. At maximum concentration of
substrate, the increase in enzyme concentration increases the reaction rate.
Therefore, the measurement of the enzymatic activity is conducted with substrate
concentration in excess.

E S E S

E

P
E + P  ES  E + P
(E = Enzyme, S = Substrate, ES = Enzyme-Substrate Complex, and P = Product)

Fig. 2.1. Catalyzation of a biochemical reaction by an enzyme (Salam, 2012).

The increase in temperature also enhances the rate of a biochemical
0
reaction. Usually, the increase in 10 C doubles the reaction rates. However, the
rate of an enzymatic reaction usually increases only < 2 times by the increase of
0
10 C. The temperature dependence of a reaction is described by Arrhenius
equation (Eq. 2.2) (Tabatabai, 1982; Sparks, 1989).

k = A.e -E/RT ....... Eq. 2.2

Abdul Kadir Salam - 2014