Abstract
Ornithine δ-aminotransferase (OAT, E.C. 2.6.1.13) catalyzes the transfer of the δ-amino group from ornithine (Orn) to α-ketoglutarate (aKG), yielding glutamate-5-semialdehyde and glutamate (Glu), and vice versa. In mammals, OAT is a mitochondrial enzyme, mainly located in the liver, intestine, brain, and kidney. In general, OAT serves to form glutamate from ornithine, with the notable exception of the intestine, where citrulline (Cit) or arginine (Arg) are end products. Its main function is to control the production of signaling molecules and mediators, such as Glu itself, Cit, GABA, and aliphatic polyamines. It is also involved in proline (Pro) synthesis. Deficiency in OAT causes gyrate atrophy, a rare but serious inherited disease, a further measure of the importance of this enzyme.
Highlights
Ornithine δ-aminotransferase (E.C. 2.6.1.13; OAT), or ornithine δ-transaminase, is an enzyme found in almost all eukaryotic organisms, from protozoans to humans, and from fungi to higher plants
OAT is believed to catalyze the formation of Orn, which is subsequently converted into Cit, and into Arg under conditions where argininosuccinate synthase (ASS) and argininosuccinate lyase (ASL) are expressed
Some authors claim that OAT is involved in resistance against some kinds of stress, especially salt stress and drought stress, through the synthesis of Pro that accumulates in vacuoles
Summary
Ornithine δ-aminotransferase (E.C. 2.6.1.13; OAT), or ornithine δ-transaminase, is an enzyme found in almost all eukaryotic organisms, from protozoans to humans, and from fungi to higher plants. This paper summarizes current knowledge on OAT, in particular in the light of recent advances in large scale analysis, and of clinical experience, and argues that viewing the role of OAT as limited to glutamate-related energy metabolism, especially in mammals, probably misses other important functions of OAT. This is evident from an examination of the pathways relating glutamate and ornithine. End Put: products of GABA: theNO: reaction by ornithine (Orn) aminotransferase (OAT) Their functions (inputrescine, italics) γ-aminobutyric acid, Pro: proline, Arg: arginine, their (in italics). Cit: functions citrulline, Put: putrescine, NO: nitric oxide. acid, Glu: glutamate, Pro: proline, Arg: arginine, citrulline, Put: nitric oxide
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
