ExplorEnz: EC 7.1.1.2

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7.1.1.2

Accepted name:

NADH:ubiquinone reductase (H⁺-translocating)

Reaction:

NADH + H⁺ + an ubiquinone + 4 H⁺_{[side 1]} = NAD⁺ + an ubiquinol + 4 H⁺_{[side 2]}

Other name(s):

ubiquinone reductase (ambiguous); type 1 dehydrogenase; complex 1 dehydrogenase; coenzyme Q reductase (ambiguous); complex I (electron transport chain); complex I (mitochondrial electron transport); complex I (NADH:Q1 oxidoreductase); dihydronicotinamide adenine dinucleotide-coenzyme Q reductase (ambiguous); DPNH-coenzyme Q reductase (ambiguous); DPNH-ubiquinone reductase (ambiguous); mitochondrial electron transport complex 1; mitochondrial electron transport complex I; NADH coenzyme Q₁ reductase; NADH-coenzyme Q oxidoreductase (ambiguous); NADH-coenzyme Q reductase (ambiguous); NADH-CoQ oxidoreductase (ambiguous); NADH-dehydrogenase (ubiquinone) (ambiguous); NADH-CoQ reductase (ambiguous); NADH-ubiquinone reductase (ambiguous); NADH-ubiquinone oxidoreductase (ambiguous); NADH-ubiquinone-1 reductase; reduced nicotinamide adenine dinucleotide-coenzyme Q reductase (ambiguous); NADH:ubiquinone oxidoreductase complex; NADH-Q6 oxidoreductase (ambiguous); electron transfer complex I; NADH₂ dehydrogenase (ubiquinone)

Systematic name:

NADH:ubiquinone oxidoreductase

Comments:

The enzyme is a very large complex that participates in electron transfer chains of mitochondria and aerobic bacteria, transferring two electrons from NADH to a ubiquinone in the membrane's ubiquinone pool while pumping additional protons across the membrane, generating proton motive force. Different reports disagree whether the enzyme pumps 3 or 4 protons. Reversed electron transport through this enzyme can reduce NAD⁺ to NADH.

Links to other databases:

BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9028-04-0

References:

1.	Hatefi, Y., Ragan, C.I. and Galante, Y.M. The enzymes and the enzyme complexes of the mitochondrial oxidative phosphorylation system. In: Martonosi, A. (Ed.), The Enzymes of Biological Membranes, 2nd edn, vol. 4, Plenum Press, New York, 1985, pp. 1–70.
2.	Herter, S.M., Kortluke, C.M. and Drews, G. Complex I of Rhodobacter capsulatus and its role in reverted electron transport. Arch. Microbiol. 169 (1998) 98–105. [DOI] [PMID: 9446680]
3.	Hunte, C., Zickermann, V. and Brandt, U. Functional modules and structural basis of conformational coupling in mitochondrial complex I. Science 329 (2010) 448–451. [DOI] [PMID: 20595580]
4.	Efremov, R.G., Baradaran, R. and Sazanov, L.A. The architecture of respiratory complex I. Nature 465 (2010) 441–445. [DOI] [PMID: 20505720]
5.	Wikstrom, M. and Hummer, G. Stoichiometry of proton translocation by respiratory complex I and its mechanistic implications. Proc. Natl. Acad. Sci. USA 109 (2012) 4431–4436. [DOI] [PMID: 22392981]

[EC 7.1.1.2 created 1961 as EC 1.6.5.3, deleted 1965, reinstated 1983, modified 2011, modified 2013, transferred 2018 to EC 7.1.1.2, modified 2023]