NADH:ubiquinone reductase (non-electrogenic)

NADH:ubiquinone reductase (non-electrogenic) (EC 1.6.5.9, NDH-2, ubiquinone reductase, coenzyme Q reductase, dihydronicotinamide adenine dinucleotide-coenzyme Q reductase, DPNH-coenzyme Q reductase, DPNH-ubiquinone reductase, NADH-coenzyme Q oxidoreductase, NADH-coenzyme Q reductase, NADH-CoQ oxidoreductase, NADH-CoQ reductase) is an enzyme with systematic name NADH:ubiquinone oxidoreductase. This enzyme catalyses the following chemical reaction:

NADH + H + a quinone

\rightleftharpoons

NAD + a quinol

The 3 substrates of this enzyme are NADH, H, and a quinone (electron acceptor), whereas its two products are NAD and a quinol (reduced acceptor).

An important example of this reaction is:

NADH + H + ubiquinone

\rightleftharpoons

NAD + ubiquinol

This enzyme is a flavoprotein (FAD). It belongs to the family of oxidoreductases, specifically those acting on NADH or NADPH with other acceptors. The systematic name of this enzyme class is NADH:(quinone-acceptor) oxidoreductase. Other names in common use include reduced nicotinamide adenine dinucleotide (quinone) dehydrogenase, NADH-quinone oxidoreductase, NADH ubiquinone oxidoreductase, DPNH-menadione reductase, D-diaphorase, and NADH2 dehydrogenase (quinone), and mitochondrial (mt) complex I. This enzyme participates in oxidative phosphorylation. Several compounds are known to inhibit this enzyme, including AMP, and 2,4-dinitrophenol. NADH dehydrogenase is involved in the first step of the electron transport chain of oxidative phosphorylation (OXPHOS). Any change in the electron transport component caused by a mutation might effect the normal electron flow. This might be leading "an increase of bifurcation and generation of superoxidase radicals and increase oxidative stress in various types of cancer cells."

In the electron transport chain NADH is mainly used to create a concentration gradient of hydrogen in order to make ATP. After NADH is oxidized to NAD, 4 hydrogens are pumped out.

Structural studies

Several structures are available of this enzyme, which is part of the respiratory chain. It is a multi-subunit enzyme in which this activity is located in the hydrophilic domain. The subunits of the membrane-embedded domain are responsible for proton translocation.

References

Berrisford JM, Sazanov LA (2009). "Structural basis for the mechanism of respiratory complex I". J Biol Chem. 284 (43): 29773–83. doi:10.1074/jbc.M109.032144. PMC 2785608. PMID 19635800.
Moller, I.M; Palmer, J.M. (1982). "Direct evidence for the presence of a rotenone-resistant NADH dehydrogenase on the inner surface of plant mitochondria". Physiologia Plantarum. 54: 267–274. doi:10.1111/j.1399-3054.1982.tb00258.x.
de Vries S, Grivell LA (September 1988). "Purification and characterization of a rotenone-insensitive NADH:Q6 oxidoreductase from mitochondria of Saccharomyces cerevisiae". European Journal of Biochemistry. 176 (2): 377–84. doi:10.1111/j.1432-1033.1988.tb14292.x. PMID 3138118.
Kerscher SJ, Okun JG, Brandt U (July 1999). "A single external enzyme confers alternative NADH:ubiquinone oxidoreductase activity in Yarrowia lipolytica". Journal of Cell Science. 112 ( Pt 14) (14): 2347–54. PMID 10381390.
Rasmusson AG, Soole KL, Elthon TE (2004). "Alternative NAD(P)H dehydrogenases of plant mitochondria". Annual Review of Plant Biology. 55: 23–39. doi:10.1146/annurev.arplant.55.031903.141720. PMID 15725055.
Yusnita, Yakob; Norsiah, Md Desa; Rahman, A. Jamal (2010-12-01). "Mutations in mitochondrial NADH dehydrogenase subunit 1 (mtND1) gene in colorectal carcinoma". The Malaysian Journal of Pathology. 32 (2): 103–110. ISSN 0126-8635. PMID 21329181.
Alberts, Bruce; Johnson, Alexander; Lewis, Julian; Raff, Martin; Roberts, Keith; Walter, Peter (2002-01-01). "Electron-Transport Chains and Their Proton Pumps". {{cite journal}}: Cite journal requires |journal= (help)

External links

NADH:ubiquinone+reductase+(non-electrogenic) at the U.S. National Library of Medicine Medical Subject Headings (MeSH)

v t e Oxidoreductases: NADH or NADPH (EC 1.6)
1.6.1: NAD/NADP	NAD(P) transhydrogenase (Si-specific) NAD(P) transhydrogenase (Re/Si-specific)
1.6.2: Heme	Methemoglobin reductase NADPH—hemoprotein reductase/Cytochrome P450 reductase NADPH—cytochrome-c2 reductase Leghemoglobin reductase
1.6.3: Oxygen	NADPH oxidase P91-PHOX Neutrophil cytosolic factor 1 Neutrophil cytosolic factor 2 Neutrophil cytosolic factor 4 dual oxidase Dual oxidase 1 Dual oxidase 2
1.6.5: Quinone or similar	NADH dehydrogenase
1.6.6: Nitrogenous group	Trimethylamine-N-oxide reductase
1.6.99: other	NADH dehydrogenase (quinone)

v t e Enzymes
Activity	Active site Binding site Catalytic triad Oxyanion hole Enzyme promiscuity Diffusion-limited enzyme Cofactor Enzyme catalysis
Regulation	Allosteric regulation Cooperativity Enzyme inhibitor Enzyme activator
Classification	EC number Enzyme superfamily Enzyme family List of enzymes
Kinetics	Enzyme kinetics Eadie–Hofstee diagram Hanes–Woolf plot Lineweaver–Burk plot Michaelis–Menten kinetics
Types	EC1 Oxidoreductases (list) EC2 Transferases (list) EC3 Hydrolases (list) EC4 Lyases (list) EC5 Isomerases (list) EC6 Ligases (list) EC7 Translocases (list)

Portal:

Biology

Category:

EC 1.6.5

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