Treatment of Enzyme Kinetic Data

Abstract Various methods of plotting allosteric data are discussed with the conclusion that plots of initial velocity divided by substrate concentration (v/S) versus the initial velocity are most convenient. This type of plot is discussed in terms of the information which can be obtained from it with respect to the parameters of an equation analogous to that proposed by Monod, Wyman, and Changeux. The model proposed by these authors is also discussed in terms of its meaning with respect to enzyme kinetic, rather than ligand binding, data. A simple extension of this model is provided by considering the possibility that different conformational forms of an enzyme may have different intrinsic activities. Other models for describing allosteric kinetic data are discussed and compared. The inconsistencies between various models are pointed out. A somewhat different mechanism from those which have previously been discussed in the literature is presented. This mechanism is for the situation which corresponds to polymerization of an enzyme in a reversible fashion and for which the polymer and monomer differ with respect to kinetic parameters such as ligand binding. An equation describing this situation for dimerization is presented and the mechanism is briefly discussed.