NAD(P)H dehydrogenase, quinone 2, also known as QR2, is a protein that in humans is encoded by the NQO2gene. It is a phase II detoxificationenzyme 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 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]
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Ostrousky O, Meged S, Loewenthal R, et al. (2004). "NQO2 gene is associated with clozapine-induced agranulocytosis". Tissue Antigens. 62 (6): 483–91. doi:10.1046/j.1399-0039.2003.00133.x. PMID14617031.
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Hsieh TC, Wang Z, Hamby CV, Wu JM (2005). "Inhibition of melanoma cell proliferation by resveratrol is correlated with upregulation of quinone reductase 2 and p53". Biochem. Biophys. Res. Commun. 334 (1): 223–30. doi:10.1016/j.bbrc.2005.06.073. PMID15993843.
Fu Y, Buryanovskyy L, Zhang Z (2005). "Crystal structure of quinone reductase 2 in complex with cancer prodrug CB1954". Biochem. Biophys. Res. Commun. 336 (1): 332–8. doi:10.1016/j.bbrc.2005.08.081. PMID16129418.
Overview of all the structural information available in the PDB for UniProt: P16083 (Ribosyldihydronicotinamide dehydrogenase [quinone]) at the PDBe-KB.