Histidine ammonia-lyase
Histidine ammonia-lyase is an enzyme that in humans is encoded by the HAL gene. Histidase converts histidine into ammonia and urocanic acid.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. The reaction is catalyzed by 3,5-dihydro-5-methyldiene-4H-imidazol-4-one, an electrophilic co-factor which is formed autocatalytically by cyclization of the protein backbone of the enzyme.Pathology
Mutations in the gene for histidase are associated with histidinemia and urocanic aciduria.
