Metalloenzyme nitrile hydratase: structure, regulation, and application to biotechnology

Nitrile hydratase (NHase), which catalyzes the hydration of nitriles to amides, has been used in the industrial production of acrylamide and nicotinamide. Recent studies on NHases, which are roughly classified into iron and cobalt types according to the metal involved, have clarified the photoactivation mechanism, the novel ligand structure of the metal-binding sites, the unique mechanism of the enzyme hyper-induction, and the occurrence of an accessory gene involved in cobalt-containing NHase formation. These detailed analyses have led to the development of biotechnological applications of NHase, including biotransformation and bioremediation.