The equilibrium dissociation constant for a reaction. For the reaction: A + B = C, at equilibrium, Kd = ([A] . [B])/[C], with dimensions of moles/litre. Kd is the reciprocal of the association constant, Ka. In ligand binding (where A is the receptor, B the ligand, and C the receptor–ligand complex), Kd is the ligand concentration that produces half-maximal response.
Subjects: Medicine and Health.