| EC |
1.3.99.33 |
| Accepted name: |
urocanate reductase |
| Reaction: |
dihydrourocanate + acceptor = urocanate + reduced acceptor |
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For diagram of histidine catabolism, click here |
| Glossary: |
urocanate = 3-(1H-imidazol-4-yl)prop-2-enoate
dihydrourocanate = 3-(1H-imidazol-4-yl)propanoate |
| Other name(s): |
urdA (gene name) |
| Systematic name: |
dihydrourocanate:acceptor oxidoreductase |
| Comments: |
The enzyme from the bacterium Shewanella oneidensis MR-1 contains a noncovalently-bound FAD and a covalently-bound FMN. It functions as part of an anaerobic electron transfer chain that utilizes urocanate as the terminal electron acceptor. The activity has been demonstrated with the artificial donor reduced methyl viologen. |
| Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, PDB |
| References: |
| 1. |
Bogachev, A.V., Bertsova, Y.V., Bloch, D.A. and Verkhovsky, M.I. Urocanate reductase: identification of a novel anaerobic respiratory pathway in Shewanella oneidensis MR-1. Mol. Microbiol. 86 (2012) 1452–1463. [DOI] [PMID: 23078170] |
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| [EC 1.3.99.33 created 2013] |
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| EC |
4.2.1.49 |
| Accepted name: |
urocanate hydratase |
| Reaction: |
3-(5-oxo-4,5-dihydro-3H-imidazol-4-yl)propanoate = urocanate + H2O |
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| 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 |
| References: |
| 1. |
Rétey, J. The urocanase story: a novel role of NAD+ as electrophile. Arch. Biochem. Biophys. 314 (1994) 1–16. [DOI] [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. [DOI] [PMID: 5784906] |
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| [EC 4.2.1.49 created 1972, modified 2001] |
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| EC |
4.3.1.3 |
| Accepted name: |
histidine ammonia-lyase |
| Reaction: |
L-histidine = urocanate + NH3 |
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| Glossary: |
urocanate = (E)-3-(imidazol-4-yl)propenoate |
| Other name(s): |
histidase; histidinase; histidine α-deaminase; L-histidine ammonia-lyase |
| Systematic name: |
L-histidine ammonia-lyase (urocanate-forming) |
| Comments: |
This enzyme is a member of the aromatic amino acid lyase family, other members of which are EC 4.3.1.23 (tyrosine ammonia-lyase), EC 4.3.1.24 (phenylalanine ammonia-lyase) and EC 4.3.1.25 (phenylalanine/tyrosine ammonia-lyase). The enzyme contains the cofactor 3,5-dihydro-5-methylidene-4H-imidazol-4-one (MIO), which is common to this family [4]. This unique cofactor is formed autocatalytically by cyclization and dehydration of the three amino-acid residues alanine, serine and glycine [5]. This enzyme catalyses the first step in the degradation of histidine and the product, urocanic acid, is further metabolized to glutamate [2,3]. |
| Links to other databases: |
BRENDA, EXPASY, GTD, KEGG, MetaCyc, PDB, CAS registry number: 9013-75-6 |
| References: |
| 1. |
Mehler, A.H. and Tabor, H. Deamination of histidine to form urocanic acid in liver. J. Biol. Chem. 201 (1953) 775–784. [PMID: 13061415] |
| 2. |
Watts, K.T., Mijts, B.N., Lee, P.C., Manning, A.J. and Schmidt-Dannert, C. Discovery of a substrate selectivity switch in tyrosine ammonia-lyase, a member of the aromatic amino acid lyase family. Chem. Biol. 13 (2006) 1317–1326. [DOI] [PMID: 17185227] |
| 3. |
Poppe, L. and Rétey, J. Friedel-Crafts-type mechanism for the enzymatic elimination of ammonia from histidine and phenylalanine. Angew. Chem. Int. Ed. Engl. 44 (2005) 3668–3688. [DOI] [PMID: 15906398] |
| 4. |
Louie, G.V., Bowman, M.E., Moffitt, M.C., Baiga, T.J., Moore, B.S. and Noel, J.P. Structural determinants and modulation of substrate specificity in phenylalanine-tyrosine ammonia-lyases. Chem. Biol. 13 (2006) 1327–1338. [DOI] [PMID: 17185228] |
| 5. |
Schwede, T.F., Rétey, J. and Schulz, G.E. Crystal structure of histidine ammonia-lyase revealing a novel polypeptide modification as the catalytic electrophile. Biochemistry 38 (1999) 5355–5361. [DOI] [PMID: 10220322] |
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| [EC 4.3.1.3 created 1961, modified 2008] |
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