Lipoic acid is a compound derived from octanoic acid that is used as a cofactor in at least five enzyme systems, and is present in at least small amounts in most foods.However, these sources are covalently bound to other molecules, and aren't usable. Due to this, supplements of lipoic acid are synthesized chemically rather than obtained through natural sources. This pathway takes place entirely in the mitochondria, and begins with octanoyl bound to an acyl-carrier protein (ACP) from fatty acid biosynthesis. It can interact with lipoyl synthase to form lipoyl-ACP, after which it interacts with putative lipoyl transease in order to form protein N6-(lipoyl)lysine. Octanoyl-ACP can also interact with those enzymes in the opposite order, first the putative lipoyltransferase 2, forming protein N6-(octanoyl)lysine, and then lipoyl synthase to form protein N6-(lipoyl)lysine. At the same time, lipoic acid can interact with a lipoate protein ligase, consisting of a currently unknown protein, adding a lipoyl-carrier protein-L-lysine, also forming a protein N6-(lipoyl)lysine. Finally, lipoic acid can form lipoyl-AMP after a reaction catalyzed by the same lipoate protein ligase, which can then interact with lipoyltransferase 1 to form the protein N6-(lipoyl)lysine. This is the final and only product of this pathway.

Lipoic Acid Metabolism References