An enzyme controlled by light: the molecular mechanism of photoreactivity in nitrile hydratase.

Extensive studies have revealed the molecular mechanism of the photoreactivity of nitrile hydratase from Rhodococcus sp. N-771. In the inactive enzyme, nitric oxide is bound to the non-heme ferric iron at the catalytic center, stabilized by a claw-like structure formed by two post-translationally modified cysteines and a serine. The inactive nitrile hydratase is activated by the photoinduced release of the nitric oxide. This result might provide a means of designing novel photoreactive chemical compounds or proteins that would be applicable to biochips and light-controlled metabolic systems.