Application of the MWC Model to Enzymes

The concerted symmetry model is much more versatile than simple sequential models described by Adair or Hill. This model is endowed by the variable values of Kr, L, and c, and therefore may provide explanations for many properties of allosteric enzymes and proteins, including 

In the following discussion, we shall review several applications of the MWC model, concerning the activation and/or inhibition of allosteric enzymes with substrates or ligands. 

It should be borne in mind that in almost all enzyme systems, the saturation functions with respect to substrates or effectors cannot be determined directly, and are only inferred from kinetic measurements. This is not the case with ligand binding to proteins, such as the binding of oxygen to hemoglobin, where the saturation of protein with the ligand can be measured directly. We shall, therefore, discuss only the most characteristic qualitative predictions of the model in its application to enzymes. 

In any enzyme system, activating or inhibitory effects are measured in terms of variations of the two kinetic constants, Km and as a function of the concentrations of substrate. A, or effectors, F. Two classes of effects may then be expected in allosteric enzymes. 

Exclusive ligand binding (Substrate has the affinity only for the R state) 

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