Urocanic acid
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| Names | |
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| IUPAC name
(E)-3-(1H-imidazol-4-yl)prop-2-enoic acid
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| Identifiers | |
104-98-3  |
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| ChEBI | CHEBI:30817  |
| ChemSpider | 643824 |
| Jmol 3D model | Interactive image |
| MeSH | Urocanic+acid |
| PubChem | 1178 |
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| Properties | |
| C6H6N2O2 | |
| Molar mass | 138.124 g/mol |
| Melting point | 225 °C (437 °F; 498 K) |
| Vapor pressure | {{{value}}} |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 verify (what is ?) |
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| Infobox references | |
Urocanic acid is an intermediate in the catabolism of L-histidine.
Contents
Metabolism
It is formed from L-histidine through the action of histidine ammonialyase (also known as histidase or histidinase) by elimination of ammonium.
In the liver, urocanic acid is transformed by urocanate hydratase (or urocanase) to 4-imidazolone-5-propionic acid and subsequently to glutamic acid.
Clinical significance
Inherited deficiency of urocanase leads to elevated levels of urocanic acid in the urine, a condition known as urocanic aciduria.
Function
Urocanic acid was detected in animal sweat and skin where, among other possible functions, it acts as an endogenous sunscreen or photoprotectant against UVB-induced DNA damage. Urocanic acid is found predominantly in the stratum corneum of the skin and it is likely that most of it is derived from filaggrin catabolism (a histidine-rich protein). When exposed to UVB irradiation, trans-urocanic acid is converted in vitro and in vivo to the cis isomer.[1] The cis form is known to activate regulatory T cells.[2]
History
Urocanic acid was first isolated in 1874 by the chemist Max Jaffé from the urine of a dog,[3][4][5] hence the name (Latin: urina = urine, and canis = dog).
See also
References
- ↑ Egawa M, Nomura J, Iwaki H: The evaluation of the amount of cis- and trans-urocanic acid in the stratum corneum by Raman spectroscopy. Photochem. Photobiol. Sci., 2010, 9, 730-733.
- ↑ Schwarz T: Mechanisms of UV-induced immunosuppression. Keio J Med 2005;54(4):165-171.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ M. Jaffe: Ueber die Urocaninsäure. In: Berichte der deutschen chemischen Gesellschaft. - Weinheim : Wiley-VCH, ISSN 0365-9496 Vol. 8 (1. 1875), p. 811-813.
- ↑ M. Jaffe: Ueber einen neuen Bestandtheil des Hundeharns. In: Berichte der deutschen chemischen Gesellschaft. - Weinheim : Wiley-VCH, ISSN 0365-9496 Vol. 7 (2. 1874), p. 1669-1673.
External links
- The Online Metabolic and Molecular Bases of Inherited Disease - Chapter 80 - An overview of disorders of histidine metabolism, including urocanic aciduria.
