InterPro domain: IPR044149

This entry includes nitrilases, cyanide hydratases (CHs) and related proteins. This subgroup belongs to a larger nitrilase superfamily comprised of nitrile- or amide-hydrolyzing enzymes and amide-condensing enzymes, which depend on a Glu-Lys-Cys catalytic triad. This superfamily has been classified in the literature based on global and structure based sequence analysis into thirteen different enzyme classes (referred to as 1-13), this subgroup corresponds to class 1 [ 1 , 2 ].

Nitrilases ( 3.5.5.1 ) are enzymes that convert nitriles into their corresponding acids and ammonia. They are widespread in microbes as well as in plants where they convert indole-3-acetonitrile to the hormone indole-3-acetic acid. A conserved cysteine has been shown [ 3 , 4 ] to be essential for enzyme activity; it seems to be involved in a nucleophilic attack on thenitrile carbon atom. Cyanide hydratase ( 4.2.1.66 ) converts HCN to formamide. In phytopathogenic fungi, it is used to avoid the toxic effect of cyanide released by wounded plants [ 5 ].

1. Catalysis in the nitrilase superfamily. Curr. Opin. Struct. Biol. 12, 775-82
2. The nitrilase superfamily: classification, structure and function. Genome Biol. 2, REVIEWS0001
3. Nitrilase in biosynthesis of the plant hormone indole-3-acetic acid from indole-3-acetonitrile: cloning of the Alcaligenes gene and site-directed mutagenesis of cysteine residues. Proc. Natl. Acad. Sci. U.S.A. 90, 247-51
4. Nitrilase from Rhodococcus rhodochrous J1. Sequencing and overexpression of the gene and identification of an essential cysteine residue. J. Biol. Chem. 267, 20746-51
5. Cloning and properties of a cyanide hydratase gene from the phytopathogenic fungus Gloeocercospora sorghi. Biochem. Biophys. Res. Commun. 187, 1048-54