Type I periplasmic-binding protein of the nitrile hydratase (NHase) system that selectively converts nitriles to corresponding amides
This group includes the type I periplasmic-binding protein of the nitrile hydratase (NHase) system that selectively converts nitriles to corresponding amides, which are subsequently converted by amidases to yield free carboxylic acids and ammonia. NHases from bacteria and fungi have been purified and characterized. In Rhodococcus sp., the nitrile hydratase operon consists of six genes encoding NHase regulator 2, NHase regulator 1, amidase, NHase alpha subunit, NHase beta subunit, and NHase activator. The operon produces a constitutive hydratase that has a broad substrate spectrum: aliphatic and aromatic nitriles, mononitriles and dinitriles, hydroxynitriles and amino-nitriles, and a constitutive amidase of equally low substrate specificity. NHases are metalloenzymes containing either cobalt or iron, and therefore can be classified into two subgroups: ferric NHases and cobalt NHases.