Urocanic acid
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| Urocanic acid | |
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| Systematic name | (E)-3-(3H-imidazol-4-yl)prop-2-enoic acid |
| Other names | 4-Imidazoleacrylic acid, urocaninic acid |
| Chemical formula | C6H6N2O2 |
| Molecular mass | 138.124 g/mol |
| Density | x.xxx g/cm3 |
| Melting point | 225°C |
| Boiling point | xx.x °C |
| CAS number | 104-98-3 |
| SMILES | C1=C(NC=N1)C=CC(=O)O |
| Disclaimer and references | |
Urocanic acid is an intermediate in the catabolism of L-histidine, from which it is formed 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. Inherited deficiency of urocanase leads to elevated levels of urocanic acid in the urine, a condition known as urocanic aciduria.
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. The cis form is known to activate suppressor T cells.
Urocanic acid was first isolated in 1874 by the chemist M. Jaffe from the urine of a dog, hence the name (Latin: urina = urine, and canis = dog).
[edit] Notes
- ↑ Jaffe, M. (1874) Concerning a new constituent in the urine of dogs. Ber. Deut. Chem. Ges. 7, 1669-1673.
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