IUBMB Enzyme Nomenclature


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


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. [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. [PMID: 20595580]

4. Efremov, R.G., Baradaran, R. and Sazanov, L.A. The architecture of respiratory complex I. Nature 465 (2010) 441-445. [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. [PMID: 22392981]

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

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