Systematic Name: 1,2-dithiolane-3-pentanoic acid
Synonyms: α-liponic acid, 5-(1,2-dithiolan-3-yl)-pentanoate, lipoic acid, 6,8-thioctic acid, 6,8-thioctate, DL-thioctic acid, DL-thioctate
|Superclasses:||a cofactor → a prosthetic group|
Lipoate is an organosulfur compound that is used as an essential cofactor by many enzyme complexes. The functional group of lipoate is a ditholane ring, which is a cyclic disulfide.
The enzyme complexes that require lipoate have a dedicated lipoyl domain, and lipoate is actually produced on this domain. The precursor octanoate molecule is first attached to a specific L-lysine residue within the lipoyl domain, and is then converted to lipoate by the enzyme lipoyl synthase, which is also the source of the two sulfur atoms.
Lipoate can be dettached from the enzyme complex by a dedicated lipoamidase, and be re-attached to the complex by the enzyme lipoate protein ligase.
Chemical Formula: C8H13O2S2
Molecular Weight: 205.31 Daltons
Monoisotopic Molecular Weight: 206.0435210736 Daltons
Standard Gibbs Free Energy of Formation (ΔfG'° in kcal/mol): 69.232506 [Latendresse13]
Reactions known to consume the compound:
Reactions known to produce the compound:
Reactions known to both consume and produce the compound:
Not in pathways:
5-aminopentanoate + (R)-lipoate ↔ dihydrolipoate + D-proline
In Reactions of unknown directionality:
In Transport reactions:
(R)-lipoate[periplasm] → (R)-lipoate[cytosol]
Enzymes activated by (R)-lipoate, sorted by the type of activation, are:Activator (Mechanism unknown) of: glycine decarboxylase [Hiraga80]
Hiraga80: Hiraga K, Kikuchi G (1980). "The mitochondrial glycine cleavage system. Purification and properties of glycine decarboxylase from chicken liver mitochondria." J Biol Chem 255(24);11664-70. PMID: 7440562
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