biology

NAD(P)H dehydrogenase (quinone)

NAD(P)H dehydrogenase (quinone) is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand NAD(P)H dehydrogenase (quinone) rather than just read about it. In short: In enzymology, a NAD(P)H dehydrogenase (quinone) (EC 1.6.5.2) is an enzyme that catalyzes the chemical reaction NAD(P)H + H+ + a quinone ⇌ {\displaystyle \rightleftharpoons } NAD(P)+ + a hydroquinone The 4 substrates of this enzyme are NADH, NADPH, H+, and quinone, whereas its 3 products are NAD+, NADP+, and hydroquinone. This enzyme belongs to the family of oxidoreductases, specifically those acting on NADH or NADP…

Key takeaways

NAD(P)H dehydrogenase (quinone) belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect NAD(P)H dehydrogenase (quinone) to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NAD(P)H dehydrogenase (quinone) from memory before moving on to harder problems.

Reference excerpt

In enzymology, a NAD(P)H dehydrogenase (quinone) (EC 1.6.5.2) is an enzyme that catalyzes the chemical reaction

NAD(P)H + H+ + a quinone ⇌ {\displaystyle \rightleftharpoons } NAD(P)+ + a hydroquinone The 4 substrates of this enzyme are NADH, NADPH, H+, and quinone, whereas its 3 products are NAD+, NADP+, and hydroquinone. 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 NAD(P)H:quinone oxidoreductase. Other names in common use include 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, and NAD(P)H:(quinone-acceptor) oxidoreductase. This enzyme participates in biosynthesis of steroids. It employs one cofactor, FAD. At least one compound, Dicumarol is known to inhibit this enzyme.

Structural studies As of late 2007, only one structure has been solved for this class of enzymes, with the PDB accession code PDB: 2F1O.

References

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. doi:10.1042/bj1050455. PMC 1198331. PMID 4171422. GIUDITTA A, STRECKER HJ (1961). "Purification and some properties of a brain diaphorase". Biochim. Biophys. Acta. 48: 10–9. doi:10.1016/0006-3002(61)90509-1. PMID 13705804. MAERKI F, MARTIUS C (1960). "[Vitamin K reductase, preparation and properties.]". Biochem. Z. 333: 111–35. PMID 13765127. Misaka E, Nakanishi K. "Studies on menadione reductase of bakers' yeast. I. Purification, crystallization and some properties". J. Biochem. Tokyo: 465–471. WOSILAIT WD (1960). "The reduction of vitamin K1 by an enzyme from dog liver". J. Biol. Chem. 235 (4): 1196–201. doi:10.1016/S0021-9258(18)69504-3. PMID 13846011. 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. doi:10.1104/pp.112.1.249. PMC 157943. PMID 12226388. 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. doi:10.1021/bi971176p. PMID 9485311. Jaiswal AK (2000). "Characterization and partial purification of microsomal NAD(P)H:quinone oxidoreductases". Arch. Biochem. Biophys. 375 (1): 62–8. doi:10.1006/abbi.1999.1650. PMID 10683249. 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. Bibcode:1995PNAS...92.8846L. doi:10.1073/pnas.92.19.8846. PMC 41064. PMID 7568029.

Illustrations

Worked examples

Example 1 — a first encounter with NAD(P)H dehydrogenase (quinone)

Start with the simplest possible case. Write down what NAD(P)H dehydrogenase (quinone) claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to NAD(P)H dehydrogenase (quinone) before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about NAD(P)H dehydrogenase (quinone) ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of NAD(P)H dehydrogenase (quinone)

In research: NAD(P)H dehydrogenase (quinone) appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses NAD(P)H dehydrogenase (quinone) in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: NAD(P)H dehydrogenase (quinone) is common in secondary-school and first-year university syllabi. It links to neighbouring topics EC 1.6.5, Enzymes of known structure, Flavoproteins, so understanding it makes those chapters shorter.
In everyday life: Look for NAD(P)H dehydrogenase (quinone) outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study NAD(P)H dehydrogenase (quinone) in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NAD(P)H dehydrogenase (quinone) means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
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Frequently asked questions

What is NAD(P)H dehydrogenase (quinone) in simple terms?

In enzymology, a NAD(P)H dehydrogenase (quinone) (EC 1.6.5.2) is an enzyme that catalyzes the chemical reaction NAD(P)H + H+ + a quinone ⇌ {\displaystyle \rightleftharpoons } NAD(P)+ + a hydroquinone The 4 substrates of this enzyme are NADH, NADPH, H+, and quinone, whereas its 3 products are NAD+…

Why does NAD(P)H dehydrogenase (quinone) matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study NAD(P)H dehydrogenase (quinone)?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on NAD(P)H dehydrogenase (quinone).