Fe-type nitrile hydratase

The characteristic features of Fe-type nitrile hydratase (NHase) from Rhodo coccus sp. N-771 are described. Through the biochemical analyses, we have f ound that nitric oxide (NO) regulates the photoreactivity of this enzyme by association with the non-heme iron center and photoinduced dissociation fr om it. The regulation is realized by a unique structure of the catalytic no n-heme iron center composed of post-translationally modified cysteine-sulfi nic (Cys-SO2H) and -sulfenic acids (Cys-SOH). To understand the biogenic me chanism and the functional role of these modifications, we constructed an o ver-expression system of whole NHase and individual subunits in Escherichia coli. The results of the studies on several recombinant NHases have shown that the Cys-SO2H oxidation of alpha C112 is indispensable for the catalyti c activity of Fe-type NHase. (C) 2001 Elsevier Science B.V. All rights rese rved.