Kinetic Analysis of Bisubstrate Mechanisms

One of the major reasons for carrying out kinetic studies on enzymes is to determine the kinetic mechanism. To achieve this, kinetic data are compared with the predicted kinetics of ail possible mechanisms, and those which do not fit are eliminated. This may seem to be a formidable task, but the number of possible, or reasonably plausible mechanisms is not large the possibihties can rapidly be narrowed and then tested, one by one, by kinetic techniques designed specifically to distinguish them. If all the techniques of enzyme kinetics are applied, one can in most cases deduce the actual kinetic mechanism with little or no ambiguity (Cleland, 1970, 1977 Dixon Webb, 1979 Fromm, 1979). 

In multisubstrate enzyme reactions, the kinetic mechanism can be predicted from effects of various compounds on the slope and on the intercept of reciprocal plots for a given varied substrate. An understanding of why patterns are observed for a given mechanism will help in the prediction of patterns for other mechanisms. To achieve this, the slope and intercept of a reciprocal plot must be measured to see how they are affected by the concentrations of various compounds. For this purpose, the kineticist may apply the following compounds  

The principal methods that employ steady-state data for distinguishing kinetic mechanisms include the following  

Intersection point analysis is much less dependable on the quality of experimental data than the first two criteria, and the Haldanes are reaUy the same for 

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