ID   1.6.5.5
DE   NADPH:quinone reductase.
AN   Quinone oxidoreductase.
AN   Zeta-crystallin.
CA   NADPH + 2 quinone = NADP(+) + 2 semiquinone.
CF   Zn(2+).
CC   -!- Specific for NADPH.
CC   -!- Catalyzes the one-electron reduction of certain quinones, with the
CC       orthoquinones 1,2-naphthoquinone and 9,10-phenanthrenequinone being
CC       the best substrates.
CC   -!- Dicoumarol (cf. EC 1.6.5.2) and nitrofurantoin are competitive
CC       inhibitors with respect to the quinone substrate.
CC   -!- The semiquinone free-radical product may be non-enzymically reduced
CC       to the hydroquinone or oxidized back to quinone in the presence of
CC       O(2).
CC   -!- Abundant in the lens of the eye of some mammalian species.
PR   PROSITE; PDOC00058;
DR   P28304, QOR1_ECOLI ;  P11415, QOR_CAVPO  ;  Q08257, QOR_HUMAN  ;
DR   Q28452, QOR_LAMGU  ;  P42865, QOR_LEIAM  ;  P47199, QOR_MOUSE  ;
DR   Q0MVN8, QOR_PIG    ;  Q5R4S7, QOR_PONAB  ;  P43903, QOR_PSEAE  ;
DR   Q6AYT0, QOR_RAT    ;  P40783, QOR_SALTY  ;  O74489, QOR_SCHPO  ;
DR   P38230, QOR_YEAST  ;  Q9AYU1, QR1_TRIVS  ;
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