Acetylornithine transaminase

In enzymology, an acetylornithine transaminase (EC 2.6.1.11) is an enzyme that catalyzes the chemical reaction

N₂-acetyl-L-ornithine 2-oxoglutarate ${\displaystyle \rightleftharpoons }$ N-acetyl-L-glutamate 5-semialdehyde L-glutamate

Thus, the two substrates of this enzyme are N2-acetyl-L-ornithine and 2-oxoglutarate, whereas its two products are N-acetyl-L-glutamate 5-semialdehyde 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 N2-acetyl-L-ornithine:2-oxoglutarate 5-aminotransferase. Other names in common use include acetylornithine delta-transaminase, ACOAT, acetylornithine 5-aminotransferase, acetylornithine aminotransferase, N-acetylornithine aminotransferase, N-acetylornithine-delta-transaminase, N2-acetylornithine 5-transaminase, N2-acetyl-L-ornithine:2-oxoglutarate aminotransferase, succinylornithine aminotransferase, and 2-N-acetyl-L-ornithine:2-oxoglutarate 5-aminotransferase. This enzyme participates in urea cycle and metabolism of amino groups. It employs one cofactor, pyridoxal phosphate.

Structural studies

As of late 2007, 6 structures have been solved for this class of enzymes, with PDB accession codes 1VEF, 1WKG, 1WKH, 2E54, 2EH6, and 2ORD.

References

• ALBRECHT AM, VOGEL HJ (1964). "Acetylornithine Delta-Transaminase. Partial Purification and Repression Behavior". J. Biol. Chem. 239: 1872–6. doi:10.1016/S0021-9258(18)91275-5. PMID 14213368.
• Vogel HJ (1953). "Path of Ornithine Synthesis in Escherichia Coli". Proc. Natl. Acad. Sci. U.S.A. 39 (7): 578–83. Bibcode:1953PNAS...39..578V. doi:10.1073/pnas.39.7.578. PMC 1063827. PMID 16589307.
• Voellmy R, Leisinger T (1975). "Dual role for N-2-acetylornithine 5-aminotransferase from Pseudomonas aeruginosa in arginine biosynthesis and arginine catabolism". J. Bacteriol. 122 (3): 799–809. doi:10.1128/JB.122.3.799-809.1975. PMC 246128. PMID 238949.