Information on EC 2.7.7.63 - lipoate-protein ligase

Requires Mg²⁺. Both 6S- and 6R-lipoates can act as substrates but there is a preference for the naturally occurring R-form. Selenolipoate, i.e. 5-(1,2-diselenolan-3-yl)pentanoic acid, and 6-sulfanyloctanoate can also act as substrates, but more slowly . This enzyme is responsible for lipoylation in the presence of exogenous lipoic acid . Lipoylation is essential for the function of several key enzymes involved in oxidative metabolism, including pyruvate dehydrogenase (E₂ domain), 2-oxoglutarate dehydrogenase (E₂ domain), the branched-chain 2-oxoacid dehydrogenases and the glycine cleavage system (H protein) . This enzyme attaches lipoic acid to the lipoyl domains of these proteins, converting apoproteins into holoproteins. It is likely that an alternative pathway, involving EC 2.3.1.181, lipoyl(octanoyl) transferase and EC 2.8.1.8, lipoyl synthase, is the normal route for lipoylation .