Urocanic acid

Urocanic acid

Chembox new
ImageFile=Urocanic acid.svg
IUPACName=3-(3"H"-imidazol-4-yl)prop-2-enoic acid
Section1= Chembox Identifiers

Section2= Chembox Properties
MolarMass=138.124 g/mol

Section3= Chembox Hazards

Urocanic acid is an intermediate in the catabolism of L-histidine.


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.


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. Jaffé from the urine of a dog, [Jaffé, M. (1874) Concerning a new constituent in the urine of dogs. "Ber. Deut. Chem. Ges." 7, 1669-1673.] hence the name (Latin: "urina" = urine, and "canis" = dog).

ee also

* Inborn error of metabolism


External links

* [http://books.mcgraw-hill.com/getommbid.php?isbn=0071459960&template=ommbid&c=80 The Online Metabolic and Molecular Bases of Inherited Disease - Chapter 80] - An overview of disorders of histidine metabolism, including urocanic aciduria.

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Look at other dictionaries:

  • urocanic acid — 4 Imidazoleacrylic acid; an acid derived from the oxidative deamination of l histidine; present in sweat and in dog s urine; elevated levels are observed in cases of urocanate hydratase deficiency. The cis form, resulting from exposure to UV… …   Medical dictionary

  • urocanic acid — noun An intermediate in the catabolism of L histidine, transformed in the liver by urocanate hydratase (or urocanase) into 4 imidazolone 5 propionic acid and subsequently to glutamic acid …   Wiktionary

  • urocanic acid — |yu̇rə|kanik , kānik noun Etymology: ur (I) + canine + ic : a crystalline acid C3H3N2CH . CHCOOH obtained first from the urine of a dog and formed by the enzymic deamination of histidine; 4(or 5) imidazole acrylic acid …   Useful english dictionary

  • urocanic acid — noun Etymology: 1ur + canine + ic; from its being first obtained from the urine of a dog Date: circa 1903 a crystalline acid C6H6N2O2 that is normally present in human skin …   New Collegiate Dictionary

  • urocanic acid — Intermediate in degradation of L histidine …   Dictionary of molecular biology

  • Urocanic aciduria — Infobox Disease Name = PAGENAME Caption = Urocanic acid DiseasesDB = 32605 ICD10 = ICD10|E|70|8|e|70 ICD9 = ICD9|270.5 ICDO = OMIM = 276880 MedlinePlus = eMedicineSubj = eMedicineTopic = MeshID = D014560 Urocanic aciduria, also called urocanate… …   Wikipedia

  • urocanic aciduria — Elevated levels of urocanic acid in the urine …   Medical dictionary

  • Glutamic acid — Glutamic acid …   Wikipedia

  • Oxaloacetic acid — Oxaloacetic acid …   Wikipedia

  • Homogentisic acid — IUPAC name (2,5 Dihydroxyphenyl)acetic acid …   Wikipedia

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