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|Molar mass||138.124 g/mol|
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
It is formed from L-histidine through the action of histidine ammonialyase (also known as histidase or histidinase) by elimination of ammonium.
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 regulatory T cells.
- Jaffé, M. (1874). "Concerning a new constituent in the urine of dogs". Ber. Deut. Chem. Ges. 7: 1669–1673.
- The Online Metabolic and Molecular Bases of Inherited Disease - Chapter 80 - An overview of disorders of histidine metabolism, including urocanic aciduria.