N-ribosyldihydronicotinamide:quinone dehydrogenase 2 (NQO2)

N-ribosyldihydronicotinamide:quinone dehydrogenase 2 (NQO2) is a cytosolic flavoprotein enzyme belonging to the thioredoxin family, primarily responsible for catalyzing the two-electron reduction of quinone substrates using dihydronicotinamide riboside (NRH) as an electron donor. It functions as a phase II detoxification enzyme to protect cells from oxidative stress and toxic quinones, and may also participate in biosynthetic processes such as vitamin K-dependent prothrombin synthesis. NQO2 is widely expressed and interacts with a range of small molecules (including resveratrol and melatonin) that inhibit its function. Disease associations include several cancers and neurodegenerative disorders due to mutations or altered expression. Its mechanism involves a ping-pong catalytic cycle with an FAD cofactor, resulting in quinone-to-hydroquinone reduction for detoxification. NQO2 remains incompletely understood with respect to physiological and pathological roles, but is considered a validated therapeutic target due to its involvement in cellular defense, metabolism, and disease processes.

Other names

NAD(P)H dehydrogenase, quinone 2Quinone reductase 2QR2DHQVDIA6NMOR2NRH dehydrogenase [quinone] 2NRH:quinone oxidoreductase 2NAD(P)H menadione oxidoreductase-1Dioxin-inducible-2Ribosyldihydronicotinamide dehydrogenase [quinone]EC 1.10.5.1NAD(P)H quinone dehydrogenase 2

Competitive or non-competitive inhibition of quinone reductase activity (drugs such as resveratrol and melatonin act as inhibitors). Modifying quinone metabolism and limiting the formation of reactive oxygen species by blocking reduction of quinone substrates. Role in detoxification and metabolic conjugation by directly reducing quinones to hydroquinones.