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α-Ketoglutaric acid (2-oxoglutaric acid) is one of two ketone derivatives of glutaric acid. The term "ketoglutaric acid," when not further qualified, almost always refers to the alpha variant. β-Ketoglutaric acid varies only by the position of the ketone functional group, and is much less common.
|Preferred IUPAC name
3D model (JSmol)
CompTox Dashboard (EPA)
|Molar mass||146.11 g/mol|
|Melting point||115 °C (239 °F; 388 K)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
α-Ketoglutarate is a key intermediate in the Krebs cycle, coming after isocitrate and before succinyl CoA. Anaplerotic reactions can replenish the cycle at this juncture by synthesizing α-ketoglutarate from transamination of glutamate, or through action of glutamate dehydrogenase on glutamate.
Formation of amino acidsEdit
Glutamine is synthesized from glutamate by glutamine synthetase, which utilizes adenosine triphosphate to form glutamyl phosphate; this intermediate is attacked by ammonia as a nucleophile giving glutamine and inorganic phosphate. Proline, arginine, and lysine (in some organisms) are other amino acids synthesized as well. These three amino acids derive from glutamate with the addition of further steps or enzymes to facilitate reactions.
Another function is to combine with nitrogen released in cells, therefore preventing nitrogen overload.
α-Ketoglutarate is one of the most important nitrogen transporters in metabolic pathways. The amino groups of amino acids are attached to it (by transamination) and carried to the liver where the urea cycle takes place.
α-Ketoglutarate is transaminated, along with glutamine, to form the excitatory neurotransmitter glutamate. Glutamate can then be decarboxylated (requiring vitamin B6) into the inhibitory neurotransmitter gamma-aminobutyric acid.
Relationship to molecular oxygenEdit
Acting as a co-substrate for α-ketoglutarate-dependent hydroxylase, it also plays important function in oxidation reactions involving molecular oxygen.
Molecular oxygen (O2) directly oxidizes many compounds to produce useful products in an organism, such as antibiotics, in reactions catalyzed by oxygenases. In many oxygenases, α-ketoglutarate helps the reaction by being oxidized with the main substrate. EGLN1, one of the α-ketoglutarate-dependent oxygenases, is an O2 sensor, informing the organism the oxygen level in its environment.[clarification needed]
In combination with molecular oxygen, alpha-ketoglutarate is one of the requirements for the hydroxylation of proline to hydroxyproline in the production of type 1 collagen.
A study released linked α-ketoglutarate with significantly increased lifespan in nematode worms. 
A study showed that α-ketoglutarate promotes TH1 differentiation and depletion of glutamine (by depleting its metabolite, α-ketoglutarate favors treg (regulatory T-cell) differentiation. It might play a role in skewing the balance in favor of tregs in the setting of the amino acid deprivation that can be seen in the tumor microenvironment.
α-Ketoglutarate can be produced by:
- Oxidative decarboxylation of isocitrate by isocitrate dehydrogenase
- Oxidative deamination of glutamate by glutamate dehydrogenase
- From galacturonic acid by the organism Agrobacterium tumefaciens
Alpha-ketoglutarate can be used to produce:
Interactive pathway mapEdit
Click on genes, proteins and metabolites below to link to respective articles. [§ 1]
- Merck Index, 13th Edition, 5320.
- Ledwidge, Richard; Blanchard, John S. (1999). "The Dual Biosynthetic Capability of N-Acetylornithine Aminotransferase in Arginine and Lysine Biosynthesis†". Biochemistry. 38 (10): 3019–3024. doi:10.1021/bi982574a. PMID 10074354.
- "Does infectious fever relieve autistic behavior by releasing glutamine from skeletal muscles as provisional fuel?". Archived from the original on 2014-05-19. Retrieved 2014-05-19.
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- Chin, RM; Fu, X; Pai, MY; Vergnes, L; Hwang, H; Deng, G; Diep, S; Lomenick, B; Meli, VS; Monsalve, GC; Hu, E; Whelan, SA; Wang, JX; Jung, G; Solis, GM; Fazlollahi, F; Kaweeteerawat, C; Quach, A; Nili, M; Krall, AS; Godwin, HA; Chang, HR; Faull, KF; Guo, F; Jiang, M; Trauger, SA; Saghatelian, A; Braas, D; Christofk, HR; Clarke, CF; Teitell, MA; Petrascheck, M; Reue, K; Jung, ME; Frand, AR; Huang, J (2014). "The metabolite α-ketoglutarate extends lifespan by inhibiting ATP synthase and TOR". Nature. 510 (7505): 397–401. Bibcode:2014Natur.510..397C. doi:10.1038/nature13264. PMC 4263271. PMID 24828042.
- Klysz, Dorota; Tai, Xuguang (29 September 2015). "Glutamine-dependent α-ketoglutarate production regulates the balance between T helper 1 cell and regulatory T cell generation". Science Signaling. 8 (396): ra97. doi:10.1126/scisignal.aab2610. PMID 26420908.
- Richard, Peter; Hilditch, Satu (2009). "d-Galacturonic acid catabolism in microorganisms and its biotechnological relevance". Applied Microbiology and Biotechnology. 82 (4): 597–604. doi:10.1007/s00253-009-1870-6. ISSN 0175-7598. PMID 19159926.