Properties of Proteins pH-Dependent Inhibitor Binding

In this section we briefly review experimental and computer modeling aspects of several important pFI-dependent properties of proteins. In the computer modeling part, we focus on employing computed pfC s for the prediction of these properties. With this in mind, we start with the pH dependence of the binding of inhibitors to enzymes, which is closely related to the determination of pK s by pH-dependent kinetics methods described in the preceding section. 

An important method for investigating enzymes is to study the effect of substances that are structurally similar to the substrate on the rate of catalysis. In general, the rate is decreased by such substances, and this phenomenon is called inhibition. One type of inhibition occurs when the inhibitor binds to the same site in the free enzyme as the substrate, and because the substrate and inhibitor compete for the same binding site, this is called competitive inhibition. This can be accommodated into the simple Michaelis-Menten mechanism described by Eq. [42] by addition of the equilibrium 

Straightforward application of the steady state approximation leads to 

If Hv is plotted versus [I] at varying substrate concentrations, a series of straight lines is obtained which intersect at Kj = -[I]. Other types of plot can also be constructed.  

application of the steady state approximation leads to the rate equation of the same form as Eq. [64], namely, 

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