lipoic acid

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lipoic acid:

see coenzymecoenzyme
, any one of a group of relatively small organic molecules required for the catalytic function of certain enzymes. A coenzyme may either be attached by covalent bonds to a particular enzyme or exist freely in solution, but in either case it participates intimately in
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Lipoic Acid


6,8-epi-dithio-octanoic acid, a widespread naturally occurring coenzyme, related to enzymes of the class of oxidoreductases. It exists in the form of crystals with melting point 59°-60°C and was first isolated from bull’s liver in 1941 (30 mg of lipoic acid was obtained from 10 tons of liver).

Lipoic acid participates in the transfer of acyl groups (acid radicals) and in biological oxidation reactions (for example, oxidative decarboxylation of pyruvic and ketoglutaric acids for conversion into acetyl-CoA and succinyl-CoA, respectively, with liberation of carbon dioxide). The oxidized form of lipoic acid is transformed into a reduced form, which is then reconverted into the oxidized form upon action of a specific enzyme:

Lipoic acid is the growth factor (vitamin) in certain microorganisms; it exists in composite protein form in the cells of plant and animal tissues.

lipoic acid

[lī′pō·ik ′as·əd]
C8H14O2S2 A compound which participates in the enzymatic oxidative decarboxylation of α-keto acids in a stage between thiamine pyrophosphate and coenzyme A.
References in periodicals archive ?
Lipoamide dehydrogenase deficiency: a newly discovered cause of acute hepatitis in adults.
Congenital lacticacidemia caused by lipoamide dehydrogenase deficiency with favorable outcome.
160] of ANT, regulated by glutathione oxidation and protected by low concentration of N-ethylmaleimide (NEM) or monobromobimane [128]; Cys56 of ANT, sensitive to the redox state of the matricial pyridine nucleotides perhaps with the mediation of thioredoxin or lipoamide and also protected by NEM, not by monobromobimane [129]; external thiol groups (SH), promoting PTP opening by reaction with NEM or copper-orthophenanthroline; and [Cys.
falciparum Thioredoxin reductase (PfTrxR) , belonging to the family of dimeric flavoenzymes, which includes lipoamide dehydrogenase, glutathione reductase, and mercuric ion reductase, is a high molecular weight enzyme that reduces Thioredoxin (Trx) (7).
The result was supported by Reed (1973), who thought that lipoamide dehydrogenase was the flavoprotein component of the [alpha]-keto acid, and which was involved in Krebs cycle promoting energy metabolism.