|Superclasses:||Reactions Classified By Conversion Type → Simple Reactions → Chemical Reactions|
|Reactions Classified By Conversion Type → Simple Reactions → Chemical Reactions → Composite Reactions → Electron-Transfer-Reactions|
|Reactions Classified By Substrate → Small-Molecule Reactions|
EC Number: 126.96.36.199
Supersedes EC number: 188.8.131.52
Reaction Locations: inner membrane (sensu Gram-negative Bacteria)
The direction shown, i.e. which substrates are on the left and right sides, is in accordance with the direction in which it was curated.
Most BioCyc compounds have been protonated to a reference pH value of 7.3. Please see the PGDB Concepts Guide for more information.
Mass balance status: Balanced.
Enzyme Commission Primary Name: NAD(P)H dehydrogenase (quinone)
Enzyme Commission Synonyms: menadione reductase, phylloquinone reductase, quinone reductase, dehydrogenase, reduced nicotinamide adenine dinucleotide (phosphate, quinone), DT-diaphorase, flavoprotein NAD(P)H-quinone reductase, menadione oxidoreductase, NAD(P)H dehydrogenase, NAD(P)H menadione reductase, NAD(P)H-quinone dehydrogenase, NAD(P)H-quinone oxidoreductase, NAD(P)H: (quinone-acceptor)oxidoreductase, NAD(P)H: menadione oxidoreductase, NADH-menadione reductase, naphthoquinone reductase, p-benzoquinone reductase, reduced NAD(P)H dehydrogenase, viologen accepting pyridine nucleotide oxidoreductase, vitamin K reductase, diaphorase, reduced nicotinamide-adenine dinucleotide (phosphate) dehydrogenase, vitamin-K reductase, NAD(P)H2 dehydrogenase (quinone), NQO1, QR1, NAD(P)H:(quinone-acceptor) oxidoreductase
The reaction is a two-electron reduction of quinones to quinols.
Enzyme Commission Summary:
A flavoprotein. The enzyme catalyses a two-electron reduction and has a preference for short-chain acceptor quinones, such as ubiquinone, 1,4-benzoquinone, juglone and duroquinone [Sparla96]. The animal, but not the plant, form of the enzyme is inhibited by dicoumarol.
Instance reactions of [an electron-transfer quinone[inner membrane] + NAD(P)H + H+ → an electron-transfer quinol[inner membrane] + NAD(P)+] (184.108.40.206):
i1: NADH + a menaquinone[inner membrane] + H+ → NAD+ + a menaquinol[inner membrane] (no EC#)
i2: NADH + a ubiquinone[inner membrane] + H+ → NAD+ + an ubiquinol[inner membrane] (220.127.116.11)
Braun98a: Braun M, Bungert S, Friedrich T (1998). "Characterization of the overproduced NADH dehydrogenase fragment of the NADH:ubiquinone oxidoreductase (complex I) from Escherichia coli." Biochemistry 37(7);1861-7. PMID: 9485311
Di67: Di Prisco G, Casola L, Giuditta A (1967). "Purification and properties of a soluble reduced nicotinamide-adenine dinucleotide (phosphate) dehydrogenase from the hepatopancreas of Octopus vulgaris." Biochem J 105(2);455-60. PMID: 4171422
Li95a: Li R, Bianchet MA, Talalay P, Amzel LM (1995). "The three-dimensional structure of NAD(P)H:quinone reductase, a flavoprotein involved in cancer chemoprotection and chemotherapy: mechanism of the two-electron reduction." Proc Natl Acad Sci U S A 92(19);8846-50. PMID: 7568029
Sparla96: Sparla F, Tedeschi G, Trost P (1996). "NAD(P)H:(Quinone-Acceptor) Oxidoreductase of Tobacco Leaves Is a Flavin Mononucleotide-Containing Flavoenzyme." Plant Physiol 112(1);249-258. PMID: 12226388
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