IUBMB Enzyme Nomenclature


Accepted name: urocanate hydratase

Reaction: 3-(5-oxo-4,5-dihydro-3H-imidazol-4-yl)propanoate = urocanate + H2O

For diagram click here and probable mechanism here.

Glossary: urocanate = (E)-3-(imidazol-4-yl)propenoate

Other name(s): urocanase; 3-(5-oxo-4,5-dihydro-3H-imidazol-4-yl)propanoate hydro-lyase

Systematic name: 3-(5-oxo-4,5-dihydro-3H-imidazol-4-yl)propanoate hydro-lyase (urocanate-forming)

Comments: Contains tightly bound NAD+.

Links to other databases: BRENDA, EXPASY, GTD, KEGG, Metacyc, PDB, CAS registry number: 9014-58-8


1. Rétey, J. The urocanase story: a novel role of NAD+ as electrophile. Arch. Biochem. Biophys. 314 (1994) 1-16. [PMID: 7944380]

2. Hassall, H. and Greenberg, D.M. Urocanase (beef liver). Methods Enzymol. 17B (1971) 84-88.

3. Kaminskas, E., Kimhi, Y. and Magasanik, B. Urocanase and N-formimino-L-glutamate formiminohydrolase of Bacillus subtilis, two enzymes of the histidine degradation pathway. J. Biol. Chem. 245 (1970) 3536-3544. [PMID: 4990470]

4. Swaine, D. The effect of substrate analogues on the activity of cat liver urocanase. Biochim. Biophys. Acta 178 (1969) 609-618. [PMID: 5784906]

[EC created 1972, modified 2001]

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