In enzymology, a histidine transaminase (EC 2.6.1.38) is an enzyme that catalyzes the chemical reaction

L-histidine + 2-oxoglutarate ${\displaystyle \rightleftharpoons }$ (imidazol-5-yl)pyruvate + L-glutamate

Thus, the two substrates of this enzyme are L-histidine and 2-oxoglutarate, whereas its two products are (imidazol-5-yl)pyruvate and L-glutamate.

This enzyme belongs to the family of transferases, specifically the transaminases, which transfer nitrogenous groups. The systematic name of this enzyme class is L-histidine:2-oxoglutarate aminotransferase. Other names in common use include histidine aminotransferase, and histidine-2-oxoglutarate aminotransferase. This enzyme participates in histidine metabolism.

• Coote JG, Hassall H (1969). "The role of imidazol-5-yl-lactate-nicotinamide-adenine dinucleotide phosphate oxidoreductase and histidine-2-oxoglutarate aminotransferase in the degradation of imidazol-5-yl-lactate by Pseudomonas acidovorans". Biochem. J. 111 (2): 237–9. PMC 1187811. PMID 4303364.
• Wickremasinghe R, Hedegaard J, Roche J (1967). "Degradation de la L-histidine chez Escherichia coli B: formation de l'acide imidazolepyruvique par une histidine-transaminase". C. R. Soc. Biol. 161: 1891–1896.