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Binding selectivity is defined with respect to the binding of ligands to a substrate forming a complex. A selectivity coefficient is the equilibrium constant for the reaction of displacement by one ligand of another ligand in a complex with the substrate. Binding selectivity is of major importance in biochemistry and in chemical separation processes. == Selectivity coefficient == The concept of selectivity is used to quantify the extent to which a given substrate, A, binds two different ligands, B and C. The simplest case is where the complexes formed have 1:1 stoichiometry. Then, the two interactions may be characterized by equilibrium constants ''K''AB and ''K''AC.〔The constant used here are ''association'' constants. ''Dissociation'' constants are used in some contexts. A dissociation constant is the reciprocal of an association constant.〕 : : () represents a concentration. A selectivity coefficient is defined as the ratio of the two equilibrium constants. : The selectivity coefficient is in fact the equilibrium constant for the displacement reaction : It is easy to show that the same definition applies to complexes of a different stoichiometry, ApBq and ApCq. The greater the selectivity coefficient, the more the ligand C will displace the ligand B from the complex formed with the substrate A. An alternative interpretation is that the greater the selectivity coefficient, the lower the concentration of C that is needed to displace B from AB. Selectivity coefficients are determined experimentally by measuring the two equilibrium constants, ''K''AB and ''K''AC. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「binding selectivity」の詳細全文を読む スポンサード リンク
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