An allosteric regulation is the biochemical regulation of an enzyme or protein by the binding of an effector molecule to the protein's inactive, or allosteric, site. These effector molecules can enhance or inhibit the protein's activity and create a conformational change in the protein.
The conformational change caused by allosteric inhibitors modify the size and shape of the active site so that the molecule upon which the enzyme acts cannot bind to it. Allosteric activators alter the active site to increase the substrate's affinity for the enzyme. Allosteric sites are currently being use to develop safer medications to treat a variety of illnesses, including hemolytic anemia and schizophrenia.