PROSITE documentation PDOC00712
Nitrilases / cyanide hydratase signatures


Nitrilases (EC 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 [1,2] to be essential for enzyme activity; it seems to be involved in a nucleophilic attack on the nitrile carbon atom.

Cyanide hydratase (EC converts HCN to formamide. In phytopathogenic fungi, it is used to avoid the toxic effect of cyanide released by wounded plants [3]. The sequence of cyanide hydrolase is evolutionary related to that of nitrilases.

Yeast hypothetical proteins YIL164c and YIL165c also belong to this family.

As signature patterns for these enzymes, we selected two conserved regions. The first is located in the N-terminal section while the second, which contains the active site cysteine, is located in the central section.

Last update:

November 1995 / Patterns and text revised.


Technical section

PROSITE methods (with tools and information) covered by this documentation:

NITRIL_CHT_1, PS00920; Nitrilases / cyanide hydratase signature 1  (PATTERN)

NITRIL_CHT_2, PS00921; Nitrilases / cyanide hydratase active site signature  (PATTERN)


1AuthorsKobayashi M. Izui H. Nagasawa T. Yamada H.
TitleNitrilase 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.
SourceProc. Natl. Acad. Sci. U.S.A. 90:247-251(1993).
PubMed ID8419930

2AuthorsKobayashi M. Komeda H. Yanaka N. Nagasawa T. Yamada H.
TitleNitrilase from Rhodococcus rhodochrous J1. Sequencing and overexpression of the gene and identification of an essential cysteine residue.
SourceJ. Biol. Chem. 267:20746-20751(1992).
PubMed ID1400390

3AuthorsWang P. VanEtten H.D.
TitleCloning and properties of a cyanide hydratase gene from the phytopathogenic fungus Gloeocercospora sorghi.
SourceBiochem. Biophys. Res. Commun. 187:1048-1054(1992).
PubMed ID1382413

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