The 2-oxoglutarate dehydrogenase system is a large enzyme complex that belongs to the 2-oxoacid dehydrogenase system family, which also includes EC 184.108.40.206, branched-chain alpha-keto acid dehydrogenase system, EC 220.127.116.11, pyruvate dehydrogenase system, EC 18.104.22.168, glycine cleavage system, and EC 22.214.171.124, acetoin dehydrogenase system. With the exception of the glycine cleavage system, which contains 4 components, the 2-oxoacid dehydrogenase systems share a common structure, consisting of three main components, namely a 2-oxoacid dehydrogenase (E1), a dihydrolipoamide acyltransferase (E2), and a dihydrolipoamide dehydrogenase (E3). This enzyme system converts 2-oxoglutarate to succinyl-CoA and produces NADH and CO2 in a complicated series of irreversible reactions. The reaction catalysed by this system is the sum of three activities: EC 126.96.36.199, oxoglutarate dehydrogenase (succinyl-transferring) (E1), EC 188.8.131.52, dihydrolipoyllysine-residue succinyltransferase (E2) and EC 184.108.40.206, dihydrolipoyl dehydrogenase (E3).
Shim da J, Nemeria NS, Balakrishnan A, Patel H, Song J, Wang J, Jordan F, Farinas ET.
Assignment of function to histidines 260 and 298 by engineering the E1 component of the Escherichia coli 2-oxoglutarate dehydrogenase complex; substitutions that lead to acceptance of substrates lacking the 5-carboxyl group.