Chemical specificity

Chemical specificity is the ability of a protein's binding site to bind specific ligands. The fewer ligands a protein can bind, the greater its specificity.

Specificity has its technical basis as an experimental measurement in enzyme kinetics, where the strength of binding between a given protein and ligand can be described by a dissociation constant, which characterizes the balance between bound and unbound states for the protein-ligand system. In the context of a single enzyme and a pair of binding molecules, the two ligands can be compared as stronger or weaker ligands (for the enzyme) on the basis of their dissociation constants. (A lower value corresponds to a stronger binding.)