In enzymology, a NADPH:quinone reductase () is an enzyme that catalyzes the chemical reaction NADPH + H+ + 2quinone NADP+ + 2semiquinone The 3 substrates of this enzyme are NADPH, H+, and quinone, whereas its two products are NADP+ and semiquinone. This enzyme belongs to the family of oxidoreductases, specifically those acting on NADH or NADPH with a quinone or similar compound as acceptor. The systematic name of this enzyme class is NADPH:quinone oxidoreductase. This enzyme is also called NADPH2:quinone reductase. Structural studies As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes , , and . References EC 1.6.5 NADPH-dependent enzymes Enzymes of known structure