On the Interpretation of Equilibrium Binding Studies

Abstract

Equilibrium binding curves are discussed on the basis of their fundamental equations. The shape of these curves is not influenced by the number of conformational states of the receptor-ligand complexes. In contrast, the number of binding sites determines the shape of the equilibrium binding curve. For example, a curved Scat-chard plot establishes the existence of more than one binding site at the receptor but cannot yield information on the number of conformational states. If there are discrepancies between equilibrium binding and equilibrium dose-response curves they indicate that the response is not initiated by the overall binding process. They may be explained assuming that only one particular receptor-ligand complex (e.g. the fully saturated one) will initiate the physiological response.