|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: 220.127.116.11
Supersedes EC number: 18.104.22.168
Reaction Locations: inner membrane (sensu Gram-negative Bacteria)
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, 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, and some reactions have been computationally balanced for hydrogen by adding free protons. 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)+] (22.214.171.124):
i1: NADH + a menaquinone[inner membrane] + H+ → NAD+ + a menaquinol[inner membrane] (no EC#)
i2: NADH + an ubiquinone[inner membrane] + H+ → NAD+ + an ubiquinol[inner membrane] (126.96.36.199)
Braun98: 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
©2014 SRI International, 333 Ravenswood Avenue, Menlo Park, CA 94025-3493