alpha-Ketoglutaric acid

α-Ketoglutaric acid

Names
IUPAC name 2-Oxopentanedioic acid
Other names 2-Ketoglutaric acid alpha-Ketoglutaric acid 2-Oxoglutaric acid Oxoglutaric acid
Identifiers
CAS Number	328-50-7 Y
ChEBI	CHEBI:30915 Y
ChEMBL	ChEMBL1686 Y
ChemSpider	50 Y
DrugBank	DB02926 N
IUPHAR/BPS	3636
Jmol 3D model	Interactive image
KEGG	C00026 Y
MeSH	alpha-ketoglutaric+acid
PubChem	51
UNII	8ID597Z82X Y
InChI InChI=1S/C5H6O5/c6-3(5(9)10)1-2-4(7)8/h1-2H2,(H,7,8)(H,9,10) Y Key: KPGXRSRHYNQIFN-UHFFFAOYSA-N Y InChI=1/C5H6O5/c6-3(5(9)10)1-2-4(7)8/h1-2H2,(H,7,8)(H,9,10) Key: KPGXRSRHYNQIFN-UHFFFAOYAN
SMILES O=C(O)C(=O)CCC(=O)O
Properties
Chemical formula	C5H6O5
Molar mass	146.11 g/mol
Melting point	115 °C (239 °F; 388 K)
Vapor pressure	{{{value}}}
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

α-Ketoglutaric 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.)

Its anion, α-ketoglutarate (α-KG, also called oxo-glutarate) is an important biological compound. It is the keto acid produced by deamination of glutamate, and is an intermediate in the Krebs cycle.

Functions

Krebs cycle

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 acids

Glutamine is synthesized from glutamate by glutamine synthetase, which utilizes an ATP to form glutamyl phosphate; this intermediate is attacked by ammonia as a nucleophile giving glutamine and inorganic phosphate.

Nitrogen transporter

Another function is to combine with nitrogen released in the cell, 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 GABA.

It is reported that high ammonia and/or high nitrogen levels may occur with high protein intake, excessive aluminum exposure, Reye's syndrome, cirrhosis, and urea cycle disorder.

It plays a role in detoxification of ammonia in brain.

Relationship to molecular oxygen

Acting as a co-substrate, 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, etc., in reactions catalyzed by oxygenases. In many oxygenases, α-ketoglutarate helps the reaction by being oxidized together with the main substrate. In fact, one of the α-ketoglutarate-dependent oxygenases is an O₂ sensor, informing the organism the oxygen level in its environment.

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.

Antioxidant

α-Ketoglutarate, which is known to be released by several cell types, decreased the levels of hydrogen peroxide, and the α-ketoglutarate was depleted and converted to succinate in cell culture media.

Longevity

A study released on May 14, 2014 links α-ketoglutarate with significantly increased lifespan in nematode worms.

Immune Regulation

A recent study has shown that α-ketoglutarate promotes TH1 differentiation and depletion of Glutamine (by depleting its metabolite α-ketoglutarate favors Treg differentiation. It might play a role in skewing the balance in favor of Tregs in the setting of amino acid deprivation that can be seen in the tumor microenvironment.

Production

α-Ketoglutarate can be produced by:

• Oxidative decarboxylation of isocitrate by isocitrate dehydrogenase;
• Oxidative deamination of glutamate by glutamate dehydrogenase.

Alpha-ketoglutarate can be used to produce:

• Creatine-alpha ketoglutarate

Interactive pathway map

Click on genes, proteins and metabolites below to link to respective articles.

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|{{{bSize}}}px|alt=TCA Cycle edit]]

File:TCACycle WP78.png

TCA Cycle edit