Lipoic acid, also known as α-lipoic acid and thioctic acid, is an organosulfur (sulfur-containing) coenzyme. Lipoic acid is an essential cofactor of dehydrogenase enzymes involved in the oxidative decarboxylation of 2-oxoacids and the glycine cleavage (glycine decarboxylase) system. Lipoic acid is derived from the 8-carbon fatty acid, octanoic acid. In most eukaryotes, lipoic acid is synthesised in mitochondrion. However, in plants, the biosynthetic pathway is present in plastids in addition to mitochondria. Lipoic acid is made in animals normally, and is essential for aerobic metabolism. Lipoic acid metabolism starts by the precursor, Octanoyl-[acyl-carrier-protein], which is made via fatty acid biosynthesis. Octanoyl-[acp] can be catalyzed by either lipoyl synthase (LipA) or lipoyl(octanoyl) transferase (LipB), to produce lipoyl-[acp] or protein N6-(octanoyl)lysine respectively. Lastly, protein N6-(lipoyl)lysine is generated via synthesis of protein N6-(octanoyl)lysine by LipA, or via the transfer of a lysine group to lipoyl-[acp] by LipB.

Lipoic Acid Metabolism References