Multiple binding equilibria

Consider the multiple binding equilibria of a ligand X with / different binding sites on a protein or pol>Tner P ... 

The binding equilibrium expressed as shown above (2.2) is actually a gross oversimplification of the situation. The heterogeneity of the binding sites and multiple valency of individual antibodies lead to formation of secondary bonds that contribute to hysteresis or ripening of the antibody-antigen complex. Its ultimate form is the polymerization of a primary complex, which happens when the antigen is also polyvalent. Formation of the polymer (precipitin reaction) renders such a reaction virtually irreversible. 

At higher temperatures transitions between these wells are superimposed to harmonic fluctuations [3,21], Non-equilibrium motions are due to the relaxation toward equilibrium. Since photodissociation creates a non-equilibrium state of the protein both type of motions can take part in the recombination process. In fact, Ansari et al. concluded [94] that the low temperature non-exponential behaviour observed for CO rebinding arises from an inhomogeneous protein population rather than a homogeneous one having multiple binding sites [93]. 

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