The transient-state kinetics of two-substrate enzyme systems operating by an ordered ternary-complex mechanism

Transient-state kinetic equations, applicable to single-turnover experiments with limiting amounts of substrate and catalytic-suicide experiments with substrates in excess to enzyme, have been derived for two-substrate enzyme reactions occurring by an ordered ternary-complex mechanism. The relative magnitude and dependence on substrate concentrations of rates and amplitudes for the exponential transients corresponding to this mechanism. It is shown that ordered ternary-complex reactions under standard assay conditions may exhibit a biphasic transient rate behaviour, and the precise conditions under which two transients can be detected are described and discussed.