Oxalosuccinic acid is a substrate of the

citric acid cycle The citric acid cycle (CAC)—also known as the Krebs cycle or the TCA cycle (tricarboxylic acid cycle)—is a series of chemical reactions to release stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and prot ...

. It is acted upon by

isocitrate dehydrogenase Isocitrate dehydrogenase (IDH) () and () is an enzyme that catalyzes the oxidative decarboxylation of isocitrate, producing alpha-ketoglutarate (α-ketoglutarate) and CO2. This is a two-step process, which involves oxidation of isocitrate (a s ...

. Salts and

ester In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ...

s of oxalosuccinic acid are known as oxalosuccinates. Oxalosuccinic acid/oxalosuccinate is an unstable 6-carbon intermediate in the

tricarboxylic acid cycle The citric acid cycle (CAC)—also known as the Krebs cycle or the TCA cycle (tricarboxylic acid cycle)—is a series of chemical reactions to release stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and protein ...

. It's a

keto acid In organic chemistry, keto acids or ketoacids (also called oxo acids or oxoacids) are organic compounds that contain a carboxylic acid group () and a ketone group ().Franz Dietrich Klingler, Wolfgang Ebertz "Oxocarboxylic Acids" in Ullmann's En ...

, formed during the oxidative decarboxylation of

isocitrate Isocitric acid is a structural isomer of citric acid. Since citric acid and isocitric acid are structural isomers, they share similar physical and chemical properties. Due to these similar properties, it is difficult to separate the isomers. Salts ...

to alpha-ketoglutarate, which is catalyzed by the enzyme isocitrate dehydrogenase. Isocitrate is first oxidized by coenzyme

NAD+ Nicotinamide adenine dinucleotide (NAD) is a coenzyme central to metabolism. Found in all living cells, NAD is called a dinucleotide because it consists of two nucleotides joined through their phosphate groups. One nucleotide contains an ade ...

to form oxalosuccinic acid/oxalosuccinate. Oxalosuccinic acid is both an alpha-keto and a beta-keto acid (an unstable compound) and it is the beta-ketoic property that allows the loss of carbon dioxide in the enzymatic reaction in conversion to the five-carbon molecule 2-oxoglutarate.

References

Tricarboxylic acids Alpha-keto acids Beta-keto acids {{biochemistry-stub