NAD(P)H dehydrogenase, quinone 2, also known as QR2, is a protein that in humans is encoded by the NQO2 gene. It is a phase II detoxification enzyme which can carry out two or four electron reductions of quinones. Its mechanism of reduction is through a ping-pong mechanism involving its FAD cofactor. Initially in a reductive phase NQO2 binds to reduced dihydronicotinamide riboside (NRH) electron donor, and mediates a hydride transfer from NRH to FAD. Then, in an oxidative phase, NQO2 binds to its quinone substrate and reduces the quinone to a dihydroquinone. Besides the two catalytic FAD, NQO2 also has two zinc ions. It is not clear whether the metal has a catalytic role. NQO2 is a paralog of NQO1.
NQO2 | |||||||||||||||||||||||||||||||||||||||||||||||||||
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Aliases | NQO2, Nqo2, NMO2, Nmor2, Ox2, DHQV, DIA6, QR2, NAD(P)H quinone dehydrogenase 2, N-ribosyldihydronicotinamide:quinone reductase 2 | ||||||||||||||||||||||||||||||||||||||||||||||||||
External IDs | OMIM: 160998 MGI: 104513 HomoloGene: 696 GeneCards: NQO2 | ||||||||||||||||||||||||||||||||||||||||||||||||||
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NQO2 is a homodimer. NQO2 can be inhibited by resveratrol.[5] One of QR2's binding sites responds to 2-iodomelatonin, and has been referred to as MT3.[6]