Transient-Phase and Steady-State Kinetics for Inhibited Enzyme Systems. II. Double-Intermediate Mechanisms

Abstract

Equations for the pre-steady state and the steady state are derived for enzyme systems in which the enzyme E, the substrate A, and an inhibitor Q are present together, the enzyme concentration being much lower than the concentrations of A and Q. Various mechanisms are considered, ail of them involving two intermediates EA and EA′ (e.g. an acyl enzyme). When the inhibition is reversible the transient phase is followed by the establishment of a steady state. It is shown how experimental pre-steady-state and steady-state results can be analyzed to obtain rate constants, including those for the binding of inhibitor. If the binding of inhibitor is irreversible there is no steady state.