Histidinol-phosphate transaminase

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histidinol-phosphate transaminase
Histidinol-phosphate transaminase homodimer, E.Coli
EC no.
CAS no.9032-98-8
IntEnzIntEnz view
ExPASyNiceZyme view
MetaCycmetabolic pathway
PDB structuresRCSB PDB PDBe PDBsum
Gene OntologyAmiGO / QuickGO

In enzymology, a histidinol-phosphate transaminase (EC is an enzyme that catalyzes the chemical reaction

L-histidinol phosphate + 2-oxoglutarate 3-(imidazol-4-yl)-2-oxopropyl phosphate + L-glutamate

Thus, the two substrates of this enzyme are L-histidinol phosphate and 2-oxoglutarate, whereas its two products are 3-(imidazol-4-yl)-2-oxopropyl phosphate 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-histidinol-phosphate:2-oxoglutarate aminotransferase. Other names in common use include imidazolylacetolphosphate transaminase, glutamic-imidazoleacetol phosphate transaminase, histidinol phosphate aminotransferase, imidazoleacetol phosphate transaminase, L-histidinol phosphate aminotransferase, histidine:imidazoleacetol phosphate transaminase, IAP transaminase, and imidazolylacetolphosphate aminotransferase. This enzyme participates in 5 metabolic pathways: histidine metabolism, tyrosine metabolism, phenylalanine metabolism, phenylalanine, tyrosine and tryptophan biosynthesis, and novobiocin biosynthesis. It employs one cofactor, pyridoxal phosphate.

Structural studies[edit]

As of late 2007, 11 structures have been solved for this class of enzymes, with PDB accession codes 1FG3, 1FG7, 1GEW, 1GEX, 1GEY, 1H1C, 1IJI, 1UU0, 1UU1, 1UU2, and 2F8J.


  • AMES BN, HORECKER BL (1956). "The biosynthesis of histidine: imidazoleacetol phosphate transaminase". J. Biol. Chem. 220 (1): 113–28. PMID 13319331.
  • Martin RG; Goldberger RF (1963). "Imidazolylacetolphosphate:L-glutamate aminotransferase. Purification and properties". J. Biol. Chem. 242 (6): 1168–1174. PMID 5337155.