F
IPR023637

Urocanase

InterPro entry
Short nameUrocanase
Overlapping
homologous
superfamilies
 

Description

Urocanase
[2]
(also known as imidazolonepropionate hydrolase or urocanate hydratase) is the enzyme that catalyses the second step in the degradation of histidine, the hydration of urocanate into imidazolonepropionate:

urocanate + H2O = 4,5-dihydro-4-oxo-5-imidazolepropanoate

Urocanase is found in some bacteria (gene hutU)
[1]
, in the liver of many vertebrates, and has also been found in the plant Trifolium repens (white clover). Urocanase is a protein of about 60 Kd, it binds tightly to NAD+and uses it as an electrophil cofactor. A conserved cysteine has been found to be important for the catalytic mechanism and could be involved in the binding of the NAD+.

This enzyme is a symmetric homodimer with tightly bound NAD+ cofactors. Each subunit consists of a typical NAD-binding domain inserted into a larger core domain that forms the dimer interface
[3]
.

References

1.Urocanase and N-formimino-L-glutamate formiminohydrolase of Bacillus subtilis, two enzymes of the histidine degradation pathway. Kaminskas E, Kimhi Y, Magasanik B. J. Biol. Chem. 245, 3536-44, (1970). PMID: 4990470

2.The urocanase story: a novel role of NAD+ as electrophile. Retey J. Arch. Biochem. Biophys. 314, 1-16, (1994). View articlePMID: 7944380

3.Structure and action of urocanase. Kessler D, Retey J, Schulz GE. J. Mol. Biol. 342, 183-94, (2004). View articlePMID: 15313616

GO terms

biological process

  • None

cellular component

  • None

Cross References

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