succinate

Succinate, or butanedioate, is the dianion of succinic acid. Succinic acid is a four-carbon dicarboxylic acid with the formula HOOC-CH2-CH2-COOH; in solution, it exists mainly as its deprotonated form, the succinate ion, with two carboxylate groups. Its salts, such as sodium succinate or disodium succinate, are common forms. The compound has two acidic protons, with pKa values around 4.2 and 5.6 for its two carboxyl groups.

In biochemistry, succinate is a key intermediate of the citric acid cycle (Krebs cycle). It is formed from succinyl-CoA by succinyl-CoA synthetase and is oxidized to fumarate by succinate dehydrogenase (part of complex II of the electron transport chain). This oxidation transfers electrons to the mitochondrial respiratory chain, contributing to ATP production. Succinate can also be transported from mitochondria to the cytosol and extracellular space, where it participates in signaling pathways.

Succinate acts as a signaling molecule by binding to the G-protein-coupled receptor SUCNR1 (GPR91). Through this receptor, it can influence processes such as angiogenesis, inflammation, and blood pressure regulation. Under conditions like ischemia or metabolic stress, intracellular succinate can accumulate and promote stabilization of hypoxia-inducible factor (HIF-1α) by inhibiting prolyl hydroxylases, linking metabolism to gene expression and adaptive responses.

Industrially, succinates are used as chemical intermediates, food additives (for example, sodium succinate as a buffering and nutrient additive), and in various pharmaceutical and cosmetic applications. Their versatility stems from the reactivity of the two carboxylate groups and the stable four-carbon backbone.