Allosteric inhibition is the process by which a regulatory molecule binds to an enzyme in a spot different from the active site for another molecule. This causes a conformational change in the active site for the second molecule, preventing binding. This process is also known as noncompetitive inhibition.
A similar process is used in allosteric activation, in which the modification of the binding site increases the binding of the second molecule. This is referred to as noncompetitive activation. In a method similar to allosteric inhibition, competitive inhibition is also used to prevent enzymatic activation. In competitive inhibition, the regulatory molecule binds to the same site as the other molecule, which prevents binding from occurring.