The binding constant is a special case of the equilibrium constant K. The equilibrium state of molecular binding, i.e. the balance between the binding and dissociation processes after infinite reaction time, may be formalized as the unbound compounds (reactants) transforming into a complex (product). This directionality of reaction defines the association equilibrium constant K_ass: In chemistry, the equilibrium constant is a quantity characterizing a chemical equilibrium in a chemical reaction which is a useful tool to determine the concentration of various reactants or products in a system where chemical equilibrium occurs. ...

(second order or bimolecular association)

Since the binding constant is related to the molar free enthalpy, it is used to quantify the affinity of binding. For this purpose, the reverse directionality is used because the resulting formalism is a reaction of first order and thus its dimension is always in mol (or mol/L). This defines the dissociation equilibrium constant K_diss: In thermodynamics and molecular chemistry, the enthalpy or heat content (denoted as Δ or ΔH, or rarely as χ) is a quotient or description of thermodynamic potential of a system, which can be used to calculate the useful work obtainable from a closed thermodynamic system under constant conditions. ... Look up affinity in Wiktionary, the free dictionary. ...

(first order dissociation)

External links

• Research group on molecular binding [1]