Steady-state approximation of enzyme activation and inhibition.

This article deals with the effects of the initial concentration of effector (inhibitor or activator) on the steady-state approximation of enzyme kinetics. The results could be summarized as follows: (1) In competitive inhibition, the increase in the initial concentration of inhibitor led to the reduction of steady state time. (2) In noncompetitive and uncompetitive inhibitions, the steady state time was not changed with the increase in the initial concentration of inhibitor. (3) In nonessential activation, the increase in the initial concentration of activator led to the reduction of steadystate time. (4) It was specially noted that in nonessential activation, even if the reaction is in the steady-state, activation constant (K(A)) can not be determined exactly unless the initial concentration of activator is very small.