Kinetics of multisubstrate reactions

Enzymes may act simultaneously on more than one S. Theoretically, the hydrolytic enzymes belong to this class, however, in practice they may be considered as monosubstrate users due to the excess of water present. 

The mechanism by which multisubstrate, non-allosteric enzymes react can be divided into two major groups (i) sequential mechanisms, in which all reactants combine with the enzyme before the reaction occurs, and, (ii) a mechanism called ping-pong by Cleland (1970), in which release of some of the P occurs before all S have combined with the enzyme. 

The sequential mechanisms can be subdivided in those which have a compulsory order and those which have a random order of S binding. These mechanisms are often described with the popular shorthand notation given by Cleland (1963), in which uni, bi, ter, etc, denote the number of S and P species. The /Cm values of the various reactants are concentration values at which half of the maxi- 

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