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 (producing a [lipoyl-carrier protein] N6-octanoyl-L-lysine), and is then converted to lipoate by the enzyme lipoate synthase, resulting in a [lipoyl-carrier protein] N6-lipoyl-L-lysine.
Lipoate synthase not only catalyzes the reaction, but is also the source of the two sulfur atoms.
All protein classes related to lipoyl-containing proteins can be collected here.
Unification Links: KEGG:C16240
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