Multiple binding sites, enzyme

It is also predicted that an allosteric inhibitor should bind noncooperatively to an enzyme that binds its substrates cooperatively, since the inhibitor binds to the predominant T state. The converse should be true for activators binding to multiple binding sites in the R state. 

Khan KK, He YQ, Domanski TL, et al. Midazolam oxidation by cytochrome P450 3 A4 and active-site mutants an evaluation of multiple binding sites and of the metabolic pathway that leads to enzyme inactivation. Mol Pharmacol 2002 61(3) 495-506. 

Figure 19.2. Schematic representation of some receptor superfamilies. This figure represents the common mechanisms of the four major receptor families discussed in Section 19.2. Example 1 is of the G protein-coupled receptor. Example 2 represents the ionotropic receptor (ligand-gated ion channel) superfamily, on which multiple binding sites are known to exist (see Figure 19.1). Example 3 represents the steroid receptor superfamily. Example 4 depicts the enzyme-linked receptor superfamily.

Enzyme with multiple binding sites cooperativity... 

Much more successful has been the tailor-making of catalysts combining cyclodextrins with transition metals or other heavy elements with multiple valencies. The cyclodextrins envelope labile catalytic centres and/or provide a binding site. Enzyme mimicry is more plausible where the specialist chemistry of a cofactor is crucial. Thus, a 2 2 -ditelluro-bis-cycloheptaamylose in its oxidised form had a kcmlKm for oxidation of 3-carboxy-4-nitrobenzenethiol only 600-fold less than that of glutathione peroxidase oxidising glutathione -but even here the mimicry is not close, as the enzyme uses a selenium, not a tellurium, cofactor. 

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