Histidine ammonia-lyase
Template:Cs1 config Template:Infobox gene Template:Infobox enzyme Histidine ammonia-lyase (EC 4.3.1.3, histidase, histidinase) is an enzyme that in humans is encoded by the HAL gene.[1][2] It converts histidine into ammonia and urocanic acid. Its systematic name is L-histidine ammonia-lyase (urocanate-forming).
Function
Histidine ammonia-lyase is a cytosolic enzyme catalyzing the first reaction in histidine catabolism, the nonoxidative deamination of L-histidine to trans-urocanic acid.[1] The reaction is catalyzed by 3,5-dihydro-5-methyldiene-4H-imidazol-4-one (MIO), an electrophilic cofactor which is formed autocatalytically by cyclization of the protein backbone of the enzyme.[3]
Pathology
Mutations in the gene for histidase are associated with histidinemia and urocanic aciduria.
See also
- Phenylalanine ammonia-lyase, another enzyme that contains the MIO cofactor
References
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Further reading
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External links
This article incorporates text from the United States National Library of Medicine, which is in the public domain.
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