lipoic acid


lipoic acid
Functions as the amide (lipoamide) in the disulfide (–S–S–) form in the transfer of “active aldehyde” (acetyl), the two-carbon fragment resulting from decarboxylation of pyruvate from α-hydroxyethylthiamin pyrophosphate to acetyl-CoA, itself being reduced to the dithiol form ( i.e., dihydrolipoic acid) in the process; present in yeast and liver extracts, and may be useful in the treatment of mushroom poisoning. L. is also an essential component of other α-keto acid dehydrogenase complexes. SYN: acetate replacement factor, ovoprotogen, protogen, protogen A, pyruvate oxidation factor, thioctic acid.

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li·po·ic acid li-.pō-ik-, lī- n any of several microbial growth factors esp a crystalline compound C8H14O2S2 that is essential for the oxidation of alpha-keto acids (as pyruvic acid) in metabolism called also protogen

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a sulphur-containing compound that can be readily interconverted to and from its reduced form, dihydrolipoic acid. Lipoic acid functions in carbohydrate metabolism as one of the coenzyme in the oxidative decarboxylation of pyruvate and other a-keto acids.

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lipo·ic ac·id (lip-oґik) a necessary cofactor of the pyruvate dehydrogenase, branched-chain α-keto acid dehydrogenase, and α-ketoglutarate dehydrogenase complexes; it contains a reactive disulfide group that can bind and transfer reaction intermediates. In the enzyme complexes it occurs as lipoamide (q.v.). It is used as a dietary supplement for its antioxidant properties. Called also α-lipoic acid.

Medical dictionary. 2011.