succinic

Succinic, in scientific contexts, usually refers to succinic acid or its derivatives. Succinic acid, or butanedioic acid, is a four-carbon dicarboxylic acid with the formula HOOC-CH2-CH2-COOH. It exists as a hygroscopic, colorless solid and can lose two protons in solution, giving two pKa values (approximately 4.2 and 5.6). Its salts and esters are widely studied and used in industry and biology.

In biochemistry, succinic acid is a central metabolite of cellular respiration. It is produced in the citric acid cycle (Krebs cycle) from succinyl-CoA and is subsequently oxidized to fumarate by succinate dehydrogenase, a member of the mitochondrial electron transport chain. This conversion links the cycle to energy production, yielding reduced coenzymes that drive ATP synthesis. Under certain conditions, such as hypoxia or mitochondrial dysfunction, succinate can accumulate and participate in signaling pathways, including stabilization of hypoxia-inducible factors; it is also discussed as an oncometabolite in some disease contexts. In addition to its metabolic roles, succinyl groups participate in post-translational modifications of proteins through succinylation.

Industrial production and applications vary. Succinic acid is produced by chemical synthesis or microbial fermentation and serves as a chemical intermediate for the manufacture of polyesters (such as biodegradable polymers), solvents, and fragrances. Salts and esters of succinic acid are used in food, pharmaceutical, and cosmetic applications as acidity regulators, buffering agents, or excipients. The term “succinic” thus spans a small molecule with significant biological importance and a range of practical uses in chemistry and industry.