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.
Its anion, α-ketoglutarate (α-KG, also called 2-oxoglutarate, or 2OG) is an important biological compound. It is the keto acid produced by deamination of glutamate, and is an intermediate in the Krebs cycle.