Enzyme Nomenclature

Continued from EC 1.5

EC 1.6

ACTING ON NADH OR NADPH

Sections

EC 1.6.1 With NAD+ or NADP+ as acceptor
EC 1.6.2 With a heme protein as acceptor
EC 1.6.3 With oxygen as acceptor
EC 1.6.4 With a disulfide as acceptor
EC 1.6.5 With a quinone or similar compound as acceptor
EC 1.6.6 With a nitrogenous group as acceptor
EC 1.6.8 With a flavin as acceptor
EC 1.6.99 With unknown physiological acceptors


EC 1.6.1 With NAD+ or NADP+ as acceptor

Contents

EC 1.6.1.1 NAD(P)+ transhydrogenase (Si-specific)
EC 1.6.1.2 NAD(P)+ transhydrogenase (Re/Si-)
EC 1.6.1.3 NAD(P)+ transhydrogenase
EC 1.6.1.4 NAD(P)+ transhydrogenase (ferredoxin)
EC 1.6.1.5 proton-translocating NAD(P)+ transhydrogenase


EC 1.6.1.1

Accepted name: NAD(P)+ transhydrogenase (Si-specific)

Reaction: NADPH + NAD+ = NADP+ + NADH

Other name(s): pyridine nucleotide transhydrogenase; transhydrogenase; NAD(P)+ transhydrogenase; nicotinamide adenine dinucleotide (phosphate) transhydrogenase; NAD+ transhydrogenase; NADH transhydrogenase; nicotinamide nucleotide transhydrogenase; NADPH-NAD+ transhydrogenase; pyridine nucleotide transferase; NADPH-NAD+ oxidoreductase; NADH-NADP+-transhydrogenase; NADPH:NAD+ transhydrogenase; H+-Thase; non-energy-linked transhydrogenase; NADPH:NAD+ oxidoreductase (B-specific); NAD(P)+ transhydrogenase (B-specific)

Systematic name: NADPH:NAD+ oxidoreductase (Si-specific)

Comments: The enzyme from Azotobacter vinelandii is a flavoprotein (FAD). It is Si-specific with respect to both NAD+ and NADP+. Also acts on deamino coenzymes [cf. EC 1.6.1.2 NAD(P)+ transhydrogenase (Re/Si-specific)].

Links to other databases: BRENDA, EXPASY, GTD, KEGG, Metacyc, CAS registry number: 9014-18-0

References:

1. Humphrey, G.F. The distribution and properties of transhydrogenase from animal tissues. Biochem. J. 65 (1957) 546-550. [PMID: 13412660]

2. You, K.-S. Stereospecificity for nicotinamide nucleotides in enzymatic and chemical hydride transfer reactions. CRC Crit. Rev. Biochem. 17 (1985) 313-451. [PMID: 3157549]

[EC 1.6.1.1 created 1961, modified 1986, modified 2013]

EC 1.6.1.2

Accepted name: NAD(P)+ transhydrogenase (Re/Si-specific)

Reaction: NADPH + NAD+ = NADP+ + NADH

Other name(s): pyridine nucleotide transhydrogenase; transhydrogenase; NAD(P)+ transhydrogenase; nicotinamide adenine dinucleotide (phosphate) transhydrogenase; NAD+ transhydrogenase; NADH transhydrogenase; nicotinamide nucleotide transhydrogenase; NADPH-NAD+ transhydrogenase; pyridine nucleotide transferase; NADPH-NAD+ oxidoreductase; NADH-NADP+-transhydrogenase; NADPH:NAD+ transhydrogenase; H+-Thase; energy-linked transhydrogenase; NAD(P) transhydrogenase (AB-specific); NAD(P)+ transhydrogenase (AB-specific); NADPH:NAD+ oxidoreductase (AB-specific)

Systematic name: NADPH:NAD+ oxidoreductase (Re/Si-specific)

Comments: The enzyme from heart mitochondria is Re-specific with respect to NAD+ and Si-specific with respect to NADP+ [cf. EC 1.6.1.1 NAD(P)+ transhydrogenase (Si-specific)].

Links to other databases: BRENDA, EXPASY, KEGG, PDB, CAS registry number: 9014-18-0, 9072-60-0

References:

1. Fisher, R.R. and Earle, S.R. Membrane-bound pyridine dinucleotide transhydrogenases. In: Everse, J., Anderson, B. and You, K. (Eds), The Pyridine Nucleotide Coenzymes, The Pyridine Nucleotide Coenzymes, New York, 1982, pp. 279-324.

2. You, K.-S. Stereospecificity for nicotinamide nucleotides in enzymatic and chemical hydride transfer reactions. CRC Crit. Rev. Biochem. 17 (1985) 313-451. [PMID: 3157549]

[EC 1.6.1.2 created 1986, modified 2013]

EC 1.6.1.3

Accepted name: NAD(P)+ transhydrogenase

Reaction: NADPH + NAD+ = NADP+ + NADH

Other name(s): pyridine nucleotide transhydrogenase; transhydrogenase (ambiguous); nicotinamide adenine dinucleotide (phosphate) transhydrogenase (ambiguous); NAD+ transhydrogenase (ambiguous); NADH transhydrogenase (misleading); nicotinamide nucleotide transhydrogenase (ambiguous); NADPH-NAD+ transhydrogenase (ambiguous); pyridine nucleotide transferase (ambiguous); NADPH-NAD+ oxidoreductase (ambiguous); NADH-NADP+-transhydrogenase (ambiguous); NADPH:NAD+ transhydrogenase; H+-Thase (ambiguous); non-energy-linked transhydrogenase (ambiguous)

Systematic name: NADPH:NAD+ oxidoreductase

Comments: The enzyme catalyses the NADPH-driven reduction of NAD+. This entry stands for enzymes whose stereo-specificity with respect to NADPH is not known. [cf. EC 1.6.1.1, NAD(P)+ transhydrogenase (Si-specific) and EC 1.6.1.2 NAD(P)+ transhydrogenase (Re/Si-specific)].

Links to other databases: BRENDA, EXPASY, KEGG Metacyc, CAS registry number:

References:

1. Keister D.L., San Pietro A., Stolzenbach F.E. Pyridine nucleotide transhydrogenase from spinach. I. Purification and properties. J. Biol. Chem. 235 (1960) 2989-2996. [PMID: 13752224]

[EC 1.6.1.3 created 2013]

EC 1.6.1.4

Accepted name: NAD(P)+ transhydrogenase (ferredoxin)

Reaction: NADH + H+ + 2 NADP+ + 2 reduced ferredoxin [iron-sulfur] cluster = NAD+ + 2 NADPH + 2 oxidized ferredoxin [iron-sulfur] cluster

Other name(s): NADH-dependent reduced ferredoxin:NADP+ oxidoreductase

Systematic name: NADH:NADP+, ferredoxin oxidoreductase

Comments: The iron-sulfur flavoprotein complex, isolated from the bacterium Clostridium kluyveri, couples the exergonic reduction of NADP+ with reduced ferredoxin and the endergonic reduction of NADP+ with NADH.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:

References:

1. Wang, S., Huang, H., Moll, J. and Thauer, R.K. NADP+ reduction with reduced ferredoxin and NADP+ reduction with NADH are coupled via an electron-bifurcating enzyme complex in Clostridium kluyveri. J. Bacteriol. 192 (2010) 5115-5123. [PMID: 20675474]

[EC 1.6.1.4 created 2015]

EC 1.6.1.5

Accepted name: proton-translocating NAD(P)+ transhydrogenase

Reaction: NADPH + NAD+ + H+[side 1] = NADP+ + NADH + H+[side 2]

Other name(s): pntA (gene name); pntB (gene name); NNT (gene name)

Systematic name: NADPH:NAD+ oxidoreductase (H+-transporting)

Comments: The enzyme is a membrane bound proton-translocating pyridine nucleotide transhydrogenase that couples the reversible reduction of NADP by NADH to an inward proton translocation across the membrane. In the bacterium Escherichia coli the enzyme provides a major source of cytosolic NADPH. Detoxification of reactive oxygen species in mitochondria by glutathione peroxidases depends on NADPH produced by this enzyme.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:

References:

1. Clarke, D.M. and Bragg, P.D. Cloning and expression of the transhydrogenase gene of Escherichia coli. J. Bacteriol. 162 (1985) 367-373. [PMID: 3884596]

2. Clarke, D.M. and Bragg, P.D. Purification and properties of reconstitutively active nicotinamide nucleotide transhydrogenase of Escherichia coli. Eur. J. Biochem. 149 (1985) 517-523. [PMID: 3891338]

3. Glavas, N.A., Hou, C. and Bragg, P.D. Involvement of histidine-91 of the β subunit in proton translocation by the pyridine nucleotide transhydrogenase of Escherichia coli. Biochemistry 34 (1995) 7694-7702. [PMID: 7779816]

4. Sauer, U., Canonaco, F., Heri, S., Perrenoud, A. and Fischer, E. The soluble and membrane-bound transhydrogenases UdhA and PntAB have divergent functions in NADPH metabolism of Escherichia coli. J. Biol. Chem. 279 (2004) 6613-6619. [PMID: 14660605]

5. Bizouarn, T., Fjellstrom, O., Meuller, J., Axelsson, M., Bergkvist, A., Johansson, C., Goran Karlsson, B. and Rydstrom, J. Proton translocating nicotinamide nucleotide transhydrogenase from E. coli. Mechanism of action deduced from its structural and catalytic properties. Biochim. Biophys. Acta 1457 (2000) 211-228. [PMID: 10773166]

6. White, S.A., Peake, S.J., McSweeney, S., Leonard, G., Cotton, N.P. and Jackson, J.B. The high-resolution structure of the NADP(H)-binding component (dIII) of proton-translocating transhydrogenase from human heart mitochondria. Structure 8 (2000) 1-12. [PMID: 10673423]

7. Johansson, T., Oswald, C., Pedersen, A., Tornroth, S., Okvist, M., Karlsson, B.G., Rydstrom, J. and Krengel, U. X-ray structure of domain I of the proton-pumping membrane protein transhydrogenase from Escherichia coli. J. Mol. Biol. 352 (2005) 299-312. [PMID: 16083909]

8. Meimaridou, E., Kowalczyk, J., Guasti, L., Hughes, C.R., Wagner, F., Frommolt, P., Nurnberg, P., Mann, N.P., Banerjee, R., Saka, H.N., Chapple, J.P., King, P.J., Clark, A.J. and Metherell, L.A. Mutations in NNT encoding nicotinamide nucleotide transhydrogenase cause familial glucocorticoid deficiency. Nat. Genet. 44 (2012) 740-742. [PMID: 22634753]

[EC 1.6.1.5 created 2015]


EC 1.6.2 With a heme protein as acceptor

Contents

EC 1.6.2.1 now EC 1.6.99.3
EC 1.6.2.2 cytochrome-b5 reductase
EC 1.6.2.3 deleted
EC 1.6.2.4 NADPH—hemoprotein reductase
EC 1.6.2.5 NADPH—cytochrome-c2 reductase
EC 1.6.2.6 leghemoglobin reductase


[EC 1.6.2.1 Transferred entry: now EC 1.6.99.3 NADH dehydrogenase (EC 1.6.2.1 created 1961, deleted 1965)]

EC 1.6.2.2

Accepted name: cytochrome-b5 reductase

Reaction: NADH + 2 ferricytochrome b5 = NAD+ + H+ + 2 ferrocytochrome b5

Other name(s): cytochrome b5 reductase; dihydronicotinamide adenine dinucleotide-cytochrome b5 reductase; reduced nicotinamide adeninedinucleotide-cytochrome b5 reductase; NADH-ferricytochrome b5 oxidoreductase; NADH-cytochrome b5 reductase; NADH 5α-reductase ; NADH-cytochrome-b5 reductase

Systematic name: NADH:ferricytochrome-b5 oxidoreductase

Comments: A flavoprotein (FAD).

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 9032-25-1

References:

1. Mahler, H.R., Raw, I., Molinari, R. and do Amaral, D.F. Studies of electron transport enzymes. II. Isolation and some properties of a cytochrome-specific reduced diphosphopyridine nucleotide dehydrogenase from pig liver. J. Biol. Chem. 233 (1958) 230-239.

2. Strittmatter, P. Microsomal cytochrome b5 and cytochrome b5 reductase. In: Boyer, P.D., Lardy, H. and Myrbäck, K. (Eds.), The Enzymes, 2nd ed., vol. 8, Academic Press, New York, 1963, p. 113-145.

3. Strittmatter, P. and Velick, S.F. The purification and properties of microsomal cytochrome reductase. J. Biol. Chem. 228 (1957) 785-799.

[EC 1.6.2.2 created 1961]

[EC 1.6.2.3 Deleted entry: cytochrome reductase (NADPH) (EC 1.6.2.3 created 1965, deleted 1972)]

EC 1.6.2.4

Accepted name: NADPH—hemoprotein reductase

Reaction: NADPH + H+ + n oxidized hemoprotein = NADP+ + n reduced hemoprotein

Other name(s): CPR; FAD-cytochrome c reductase; NADP—cytochrome c reductase; NADP—cytochrome reductase; NADPH-dependent cytochrome c reductase; NADPH:P-450 reductase; NADPH:ferrihemoprotein oxidoreductase; NADPH—cytochrome P-450 oxidoreductase; NADPH—cytochrome c oxidoreductase; NADPH—cytochrome c reductase; NADPH—cytochrome p-450 reductase; NADPH—ferricytochrome c oxidoreductase; NADPH—ferrihemoprotein reductase; TPNH2 cytochrome c reductase; TPNH-cytochrome c reductase; aldehyde reductase (NADPH-dependent); cytochrome P-450 reductase; cytochrome c reductase (reduced nicotinamide adenine dinucleotide phosphate, NADPH, NADPH-dependent); dihydroxynicotinamide adenine dinucleotide phosphate-cytochrome c reductase; ferrihemoprotein P-450 reductase; reduced nicotinamide adenine dinucleotide phosphate-cytochrome c reductase; reductase, cytochrome c (reduced nicotinamide adenine dinucleotide phosphate)

Systematic name: NADPH:hemoprotein oxidoreductase

Comments: A flavoprotein containing both FMN and FAD. This enzyme catalyses the transfer of electrons from NADPH, an obligatory two-electron donor, to microsomal P-450 monooxygenases (e.g. EC 1.14.14.1, unspecific monooxygenase) by stabilizing the one-electron reduced form of the flavin cofactors FAD and FMN. It also reduces cytochrome b5 and cytochrome c. The number n in the equation is 1 if the hemoprotein undergoes a 2-electron reduction, and is 2 if it undergoes a 1-electron reduction.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 9023-03-4

References:

1. Haas, E., Horecker, B.L. and Hogness, T.R. The enzymatic reduction of cytochrome c, cytochrome c reductase. J. Biol. Chem. 136 (1940) 747-774.

2. Horecker, B.L. Triphosphopyridine nucleotide-cytochrome c reductase in liver. J. Biol. Chem. 183, (1950) 593-605.

3. Lu, A.Y.H., Junk, K.W. and Coon, M.J. Resolution of the cytochrome P-450-containing ω-hydroxylation system of liver microsomes into three components. J. Biol. Chem. 244, (1969) 3714-3721. [PMID: 4389465]

4. Masters, B.S.S., Kamin, H., Gibson, Q.H. and Williams, C.H., Jr. Studies on the mechanism of microsomal triphosphopyridine nucleotide-cytochrome c reductase. J. Biol. Chem. 240, (1965) 921-931.

5. Williams, C.H.,Jr. and Kamin, H. Microsomal triphosphopyridine nucleotide-cytochrome c reductase in liver. J. Biol. Chem. 237, (1962) 587-595. p> 6.Masters, B.S.S., Bilimoria, M.H, Kamen, H. and Gibson, Q.H. The mechanism of 1- and 2-electron transfers catalyzed by reduced triphosphopyridine nucleotide-cytochrome c reductase. J. Biol. Chem. 240, (1965) 4081-4088. [PMID: 4378860]

7. Sevrioukova, I.F. and Peterson, J.A. NADPH-P-450 reductase: Structural and functional comparisons of the eukaryotic and prokaryotic isoforms. Biochimie 77, (1995) 562-572. [PMID: 8589067]

8. Wang, M., Roberts, D.L., Paschke, R., Shea, T.M., Masters, B.S.S. and Kim, J.-J.P. Three-dimensional structure of NADPH-cytochrome P450 reductase: Prototype for FMN- and FAD-containing enzymes. Proc. Natl. Acad. Sci. USA 94, (1997) 8411-8416. [PMID: 9237990]

9. Munro, A.W., Noble, M.A., Robledo, L., Daff, S.N. and Chapman, S.K. Determination of the redox properties of human NADPH-cytochrome P450 reductase. Biochemistry 40, (2001) 1956-1963. [PMID: 11329262]

10. Gutierrez, A., Grunau, A., Paine, M., Munro, A.W., Wolf, C.R., Roberts, G.C.K. and Scrutton, N.S. Electron transfer in human cytochrome P450 reductase. Biochem. Soc. Trans. 31, (2003) 497-501. [PMID: 12773143]

[EC 1.6.2.4 created 1972, modified 2003]

EC 1.6.2.5

Accepted name: NADPH—cytochrome-c2 reductase

Reaction: NADPH + 2 ferricytochrome c2 = NADP+ + H+ + 2 ferrocytochrome c2

Other name(s): cytochrome c2 reductase (reduced nicotinamide adenine dinucleotide phosphate); cytochrome c2 reductase (reduced nicotinamide adinine dinucleotide phosphate, NADPH)

Systematic name: NADPH:ferricytochrome-c2 oxidoreductase

Comments: A flavoprotein (FAD).

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number: 37256-32-9

References:

1. Sabo, D.J. and Orlando, J.A. Isolation, purification, and some properties of reduced nicotinamide adenine dinucleotide phosphate-cytochrome c2 reductase from Rhodopseudomonas spheroides. J. Biol. Chem. 243 (1968) 3742-3749. [PMID: 4385431]

[EC 1.6.2.5 created 1972]

EC 1.6.2.6

Accepted name: leghemoglobin reductase

Reaction: NAD(P)H + H+ + 2 ferrileghemoglobin = NAD(P)+ + 2 ferroleghemoglobin

Other name(s): ferric leghemoglobin reductase

Systematic name: NAD(P)H:ferrileghemoglobin oxidoreductase

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number: 60440-35-9

References:

1. Saari, L.L. and Klucas, R.V. Ferric leghemoglobin reductase from soybean root nodules. Arch. Biochem. Biophys. 231 (1984) 102-113. [PMID: 6539095]

[EC 1.6.2.6 created 1989]


EC 1.6.3 With oxygen as acceptor

Contents

EC 1.6.3.1 NAD(P)H oxidase (H2O2-forming)
EC 1.6.3.2 NAD(P)H oxidase (H2O-forming)
EC 1.6.3.3 NADH oxidase (H2O2-forming)
EC 1.6.3.4 NADH oxidase (H2O-forming)
EC 1.6.3.5 renalase

EC 1.6.3.1

Accepted name: NAD(P)H oxidase (H2O2-forming)

Reaction: NAD(P)H + H+ + O2 = NAD(P)+ + H2O2

Other name(s): THOX2; ThOX; dual oxidase; p138tox; thyroid NADPH oxidase; thyroid oxidase; thyroid oxidase 2; NADPH oxidase; NAD(P)H:oxygen oxidoreductase; NAD(P)H oxidase

Systematic name: NAD(P)H:oxygen oxidoreductase (H2O2-forming)

Comments: Requires FAD, heme and calcium. When calcium is present, this transmembrane glycoprotein generates H2O2 by transfering electrons from intracellular NAD(P)H to extracellular molecular oxygen. The electron bridge within the enzyme contains one molecule of FAD and probably two heme groups. This flavoprotein is expressed at the apical membrane of thyrocytes, and provides H2O2 for the thyroid peroxidase-catalysed biosynthesis of thyroid hormones.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number: 77106-92-4

References:

1. Moreno, J.C., Bikker, H., Kempers, M.J., van Trotsenburg, A.S., Baas, F., de Vijlder, J.J., Vulsma, T. and Ris-Stalpers, C. Inactivating mutations in the gene for thyroid oxidase 2 (THOX2) and congenital hypothyroidism. N. Engl. J. Med. 347 (2002) 95-102. [PMID: 12110737]

2. De Deken, X., Wang, D., Dumont, J.E. and Miot, F. Characterization of ThOX proteins as components of the thyroid H2O2-generating system. Exp. Cell 273 (2002) 187-196. [PMID: 11822874]

3. De Deken, X., Wang, D., Many, M.C., Costagliola, S., Libert, F., Vassart, G., Dumont, J.E. and Miot, F. Cloning of two human thyroid cDNAs encoding new members of the NADPH oxidase family. J. Biol. Chem. 275 (2000) 23227-23233. [PMID: 10806195]

4. Dupuy, C., Ohayon, R., Valent, A., Noel-Hudson, M.S., Deme, D. and Virion, A. Purification of a novel flavoprotein involved in the thyroid NADPH oxidase. Cloning of the porcine and human cDNAs. J. Biol. Chem. 274 (1999) 37265-37269. [PMID: 10601291]

5. Leseney, A.M., Deme, D., Legue, O., Ohayon, R., Chanson, P., Sales, J.P., Pires de Carvalho, D., Dupuy, C. and Virion, A. Biochemical characterization of a Ca2+/NAD(P)H-dependent H2O2 generator in human thyroid tissue. Biochimie 81 (1999) 373-380. [PMID: 10401672]

6. Dupuy, C., Virion, A., Ohayon, R., Kaniewski, J., Deme, D. and Pommier, J. Mechanism of hydrogen peroxide formation catalyzed by NADPH oxidase in thyroid plasma membrane. J. Biol. Chem. 266 (1991) 3739-3743. [PMID: 1995628]

[EC 1.6.3.1 created 2003, modified 2013]

EC 1.6.3.2

Accepted name: NAD(P)H oxidase (H2O-forming)

Reaction: 2 NAD(P)H + 2 H+ + O2 = 2 NAD(P)+ + 2 H2O

Systematic name: NAD(P)H:oxygen oxidoreductase (H2O-forming)

Comments: A flavoprotein (FAD). NADPH is a better substrate than NADH [1,3]. By removal of oxygen the enzyme is involved in aerobic tolerance in the thermophilic anaerobic archaeon Thermococcus profundus and in Giardia intestinalis, a microaerophilic single-celled parasite of the order Diplomonadida.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:

References:

1. Brown, D.M., Upcroft, J.A. and Upcroft, P. A H2O-producing NADH oxidase from the protozoan parasite Giardia duodenalis. Eur. J. Biochem. 241 (1996) 155-161. [PMID: 8898901]

2. Li, L. and Wang, C.C. A likely molecular basis of the susceptibility of Giardia lamblia towards oxygen. Mol. Microbiol. 59 (2006) 202-211. [PMID: 16359329]

3. Jia, B., Park, S.C., Lee, S., Pham, B.P., Yu, R., Le, T.L., Han, S.W., Yang, J.K., Choi, M.S., Baumeister, W. and Cheong, G.W. Hexameric ring structure of a thermophilic archaeon NADH oxidase that produces predominantly H2O. FEBS J. 275 (2008) 5355-5366. [PMID: 18959761]

4. Jia, B., Lee, S., Pham, B.P., Cho, Y.S., Yang, J.K., Byeon, H.S., Kim, J.C. and Cheong, G.W. An archaeal NADH oxidase causes damage to both proteins and nucleic acids under oxidative stress. Mol. Cells 29 (2010) 363-371. [PMID: 20213313]

[EC 1.6.3.2 created 2013]

EC 1.6.3.3

Accepted name: NADH oxidase (H2O2-forming)

Reaction: NADH + H+ + O2 = NAD+ + H2O2

Other name(s): NOX-1; H2O2-forming NADH oxidase

Systematic name: NADH:oxygen oxidoreductase (H2O2-forming)

Comments: A flavoprotein (FAD). The bacterium Streptococcus mutans contains two distinct NADH oxidases, a H2O2-forming enzyme and a H2O-forming enzyme (cf. EC 1.6.3.4, NADH oxidase (H2O-forming)) [1]. The enzymes from the anaerobic archaea Methanocaldococcus jannaschii [6] and Pyrococcus furiosus [3] also produce low amounts of H2O. Unlike EC 1.6.3.1 (NAD(P)H oxidase) it has no activity towards NADPH.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:

References:

1. Higuchi, M., Shimada, M., Yamamoto, Y., Hayashi, T., Koga, T. and Kamio, Y. Identification of two distinct NADH oxidases corresponding to H2O2-forming oxidase and H2O-forming oxidase induced in Streptococcus mutans. J. Gen. Microbiol. 139 (1993) 2343-2351. [PMID: 8254304]

2. Ward, D.E., Donnelly, C.J., Mullendore, M.E., van der Oost, J., de Vos, W.M. and Crane, E.J., 3rd. The NADH oxidase from Pyrococcus furiosus. Implications for the protection of anaerobic hyperthermophiles against oxidative stress. Eur. J. Biochem. 268 (2001) 5816-5823. [PMID: 11722568]

3. Kengen, S.W., van der Oost, J. and de Vos, W.M. Molecular characterization of H2O2-forming NADH oxidases from Archaeoglobus fulgidus. Eur. J. Biochem. 270 (2003) 2885-2894. [PMID: 12823559]

4. Yang, X. and Ma, K. Characterization of an exceedingly active NADH oxidase from the anaerobic hyperthermophilic bacterium Thermotoga maritima. J. Bacteriol. 189 (2007) 3312-3317. [PMID: 17293421]

5. Hirano, J., Miyamoto, K. and Ohta, H. Purification and characterization of thermostable H2O2-forming NADH oxidase from 2-phenylethanol-assimilating Brevibacterium sp. KU1309. Appl. Microbiol. Biotechnol. 80 (2008) 71-78. [PMID: 18521590]

6. Case, C.L., Rodriguez, J.R. and Mukhopadhyay, B. Characterization of an NADH oxidase of the flavin-dependent disulfide reductase family from Methanocaldococcus jannaschii. Microbiology 155 (2009) 69-79. [PMID: 19118348]

[EC 1.6.3.3 created 2013]

EC 1.6.3.4

Accepted name: NADH oxidase (H2O-forming)

Reaction: 2 NADH + 2 H+ + O2 = 2 NAD+ + 2 H2O

Other name(s): H2O-forming NADH oxidase; Nox-2

Systematic name: NADH:oxygen oxidoreductase (H2O-forming)

Comments: A flavoprotein (FAD). The bacterium Streptococcus mutans contains two distinct NADH oxidases, a H2O-forming enzyme and a H2O2-forming enzyme (cf. EC 1.6.3.3, NADH oxidase (H2O2-forming)) [1].

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:

References:

1. Schmidt, H.L., Stocklein, W., Danzer, J., Kirch, P. and Limbach, B. Isolation and properties of an H2O-forming NADH oxidase from Streptococcus faecalis. Eur. J. Biochem. 156 (1986) 149-155. [PMID: 3082630]

2. Higuchi, M., Shimada, M., Yamamoto, Y., Hayashi, T., Koga, T. and Kamio, Y. Identification of two distinct NADH oxidases corresponding to H2O2-forming oxidase and H2O-forming oxidase induced in Streptococcus mutans. J. Gen. Microbiol. 139 (1993) 2343-2351. [PMID: 8254304]

3. Matsumoto, J., Higuchi, M., Shimada, M., Yamamoto, Y. and Kamio, Y. Molecular cloning and sequence analysis of the gene encoding the H2O-forming NADH oxidase from Streptococcus mutans. Biosci. Biotechnol. Biochem. 60 (1996) 39-43. [PMID: 8824824]

4. Kawasaki, S., Ishikura, J., Chiba, D., Nishino, T. and Niimura, Y. Purification and characterization of an H2O-forming NADH oxidase from Clostridium aminovalericum: existence of an oxygen-detoxifying enzyme in an obligate anaerobic bacteria. Arch. Microbiol. 181 (2004) 324-330. [PMID: 15014929]

5. Zhang, Y.W., Tiwari, M.K., Gao, H., Dhiman, S.S., Jeya, M. and Lee, J.K. Cloning and characterization of a thermostable H2O-forming NADH oxidase from Lactobacillus rhamnosus. Enzyme Microb. Technol. 50 (2012) 255-262. [PMID: 22418266]

[EC 1.6.3.4 created 2013]

EC 1.6.3.5

Accepted name: renalase

Reaction: (1) 1,2-dihydro-β-NAD(P) + H+ + O2 = β-NAD(P)+ + H2O2
(2) 1,6-dihydro-β-NAD(P) + H+ + O2 = β-NAD(P)+ + H2O2

Other name(s): αNAD(P)H oxidase/anomerase (incorrect); NAD(P)H:oxygen oxidoreductase (H2O2-forming, epimerising) (incorrect)

Systematic name: dihydro-NAD(P):oxygen oxidoreductase (H2O2-forming)

Comments: Requires FAD. Renalase, previously thought to be a hormone, is a flavoprotein secreted into the blood by the kidney that oxidizes the 1,2-dihydro- and 1,6-dihydro- isomeric forms of β-NAD(P)H back to β-NAD(P)+. These isomeric forms, generated by nonspecific reduction of β-NAD(P)+ or by tautomerization of β-NAD(P)H, are potent inhibitors of primary metabolism dehydrogenases and pose a threat to normal respiration.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:

References:

1. Xu, J., Li, G., Wang, P., Velazquez, H., Yao, X., Li, Y., Wu, Y., Peixoto, A., Crowley, S. and Desir, G.V. Renalase is a novel, soluble monoamine oxidase that regulates cardiac function and blood pressure. J. Clin. Invest. 115 (2005) 1275-1280. [PMID: 15841207]

2. Beaupre, B.A., Hoag, M.R., Roman, J., Forsterling, F.H. and Moran, G.R. Metabolic function for human renalase: oxidation of isomeric forms of β-NAD(P)H that are inhibitory to primary metabolism. Biochemistry 54 (2015) 795-806. [PMID: 25531177]

[EC 1.6.3.5 created 2014, modified 2015]


EC 1.6.4 With a disulfide as acceptor

Contents

EC 1.6.4.1 now EC 1.8.1.6
EC 1.6.4.2 now EC 1.8.1.7
EC 1.6.4.3 now EC 1.8.1.4
EC 1.6.4.4 now EC 1.8.1.8
EC 1.6.4.5 now EC 1.8.1.9
EC 1.6.4.6 now EC 1.8.1.10
EC 1.6.4.7 now EC 1.8.1.11
EC 1.6.4.8 now EC 1.8.1.12
EC 1.6.4.9 now EC 1.8.1.13
EC 1.6.4.10 now EC 1.8.1.14


[EC 1.6.4.1 Transferred entry: now EC 1.8.1.6, cystine reductase (EC 1.6.4.1 created 1961, deleted 2002)]

[EC 1.6.4.2 Transferred entry: now EC 1.8.1.7, glutathione-disulfide reductase (EC 1.6.4.2 created 1961, modified 1989, deleted 2002)]

[EC 1.6.4.3 Transferred entry: now EC 1.8.1.4 dihydrolipoamide dehydrogenase (EC 1.6.4.3 created 1961, modified 1976, deleted 1983)]

[EC 1.6.4.4 Transferred entry: now EC 1.8.1.8, protein-disulfide reductase (EC 1.6.4.4 created 1965, deleted 2002)]

[EC 1.6.4.5 Transferred entry: now EC 1.8.1.9, thioredoxin-disulfide reductase (EC 1.6.4.5 created 1972, deleted 2002)]

[EC 1.6.4.6 Transferred entry: now EC 1.8.1.10, CoA-glutathione reductase (EC 1.6.4.6 created 1972, deleted 2002)]

[EC 1.6.4.7 Transferred entry: now EC 1.8.1.11, asparagusate reductase (EC 1.6.4.7 created 1978, deleted 2002)]

[EC 1.6.4.8 Transferred entry: now EC 1.8.1.12, trypanothione-disulfide reductase (EC 1.6.4.8 created 1989, deleted 2002)]

[EC 1.6.4.9 Transferred entry: now EC 1.8.1.13, bis-γ-glutamylcystine reductase (EC 1.6.4.9 created 1992, deleted 2002)]

[EC 1.6.4.10 Transferred entry: now EC 1.8.1.14, CoA-disulfide reductase (EC 1.6.4.10 created 1992, deleted 2002)]


EC 1.6.5 With a quinone or similar compound as acceptor

Contents

EC 1.6.5.1 deleted
EC 1.6.5.2 NAD(P)H dehydrogenase (quinone)
EC 1.6.5.3 NADH:ubiquinone reductase (H+-translocating)
EC 1.6.5.4 monodehydroascorbate reductase (NADH)
EC 1.6.5.5 NADPH:quinone reductase
EC 1.6.5.6 p-benzoquinone reductase (NADPH)
EC 1.6.5.7 2-hydroxy-1,4-benzoquinone reductase

EC 1.6.5.8 NADH:ubiquinone reductase (Na+-transporting)
EC 1.6.5.9 NADH:ubiquinone reductase (non-electrogenic)
EC 1.6.5.10 NADPH dehydrogenase (quinone)
EC 1.6.5.11 NADH dehydrogenase (quinone)
EC 1.6.5.12 demethylphylloquinone reductase


[EC 1.6.5.1 Deleted entry: quinone reductase (EC 1.6.5.1 created 1961, deleted 1965)]

EC 1.6.5.2

Accepted name: NAD(P)H dehydrogenase (quinone)

Reaction: NAD(P)H + H+ + a quinone = NAD(P)+ + a hydroquinone

For diagram of reaction click here.

Other name(s): 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

Systematic name: NAD(P)H:quinone oxidoreductase

Comments: A flavoprotein. The enzyme catalyses a two-electron reduction and has a preference for short-chain acceptor quinones, such as ubiquinone, benzoquinone, juglone and duroquinone [6]. The animal, but not the plant, form of the enzyme is inhibited by dicoumarol.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 9032-20-6

References:

1. di Prisco, G., Casola, L. and Giuditta, A. Purification and properties of a soluble reduced nicotinamide-adenine dinucleotide (phosphate) dehydrogenase from the hepatopancreas of Octopus vulgaris. Biochem. J. 105 (1967) 455-460. [PMID: 4171422]

2. Giuditta, A. and Strecker, H.J. Purification and some properties of a brain diaphorase. Biochim. Biophys. Acta 48 (1961) 10-19. [PMID: 13705804]

3. Märki, F. and Martius, C. Vitamin K-Reductase, Darsellung und Eigenschaften. Biochem. Z. 333 (1960) 111-135. [PMID: 13765127]

4. Misaka, E. and Nakanishi, K. Studies on menadione reductase of bakers' yeast. I. Purification, crystallization and some properties. J. Biochem. (Tokyo) 53 (1963) 465-471.

5. Wosilait, W.D. The reduction of vitamin K1 by an enzyme from dog liver. J. Biol. Chem. 235 (1960) 1196-1201. [PMID: 13846011]

6. Sparla, F., Tedeschi, G. and Trost, P. NAD(P)H:(quinone-acceptor) oxidoreductase of tobacco leaves is a flavin mononucleotide-containing flavoenzyme. Plant Physiol. 112 (1996) 249-258. [PMID: 12226388]

7. Braun, M., Bungert, S. and Friedrich, T. Characterization of the overproduced NADH dehydrogenase fragment of the NADH:ubiquinone oxidoreductase (complex I) from Escherichia coli. Biochemistry 37 (1998) 1861-1867. [PMID: 9485311]

8. Jaiswal, A.K. Characterization and partial purification of microsomal NAD(P)H:quinone oxidoreductases. Arch. Biochem. Biophys. 375 (2000) 62-68. [PMID: 10683249]

9. Li, R., Bianchet, M.A., Talalay, P. and Amzel, L.M. 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. USA 92 (1995) 8846-8850. [PMID: 7568029]

[EC 1.6.5.2 created 1961, transferred 1965 to EC 1.6.99.2, transferred 2005 to EC 1.6.5.2]

EC 1.6.5.3

Accepted name: NADH:ubiquinone reductase (H+-translocating)

Reaction: NADH + ubiquinone + 5 H+in = NAD+ + ubiquinol + 4 H+out

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-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: A flavoprotein (FMN) containing iron-sulfur clusters. The complex is present in mitochondria and aerobic bacteria. Breakdown of the complex can release EC 1.6.99.3, NADH dehydrogenase. In photosynthetic bacteria, 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. [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 1.6.5.3 created 1961, deleted 1965, reinstated 1983, modified 2011]

EC 1.6.5.4

Accepted name: monodehydroascorbate reductase (NADH)

Reaction: NADH + H+ + 2 monodehydroascorbate = NAD+ + 2 ascorbate

Other name(s): NADH:semidehydroascorbic acid oxidoreductase; MDHA; semidehydroascorbate reductase; AFR; AFR-reductase; ascorbic free radical reductase; ascorbate free radical reductase; SOR; MDAsA reductase (NADPH) ; SDA reductase; NADH:ascorbate radical oxidoreductase; NADH-semidehydroascorbate oxidoreductase; ascorbate free-radical reductase ; NADH:AFR oxidoreductase; monodehydroascorbate reductase (NADH2)

Systematic name: NADH:monodehydroascorbate oxidoreductase

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number: 9029-26-9

References:

1. Schulze, H.-U., Schott, H.-H. and Staudinger, H. Isolierung und Charakterisierung einer NADH: Semidehydroascorbinsäure-Oxidoreduktase aus Neurospora crassa. Hoppe-Seyler's Z. Physiol. Chem. 353 (1972) 1931-1942. [PMID: 4405497]

[EC 1.6.5.4 created 1961]

EC 1.6.5.5

Accepted name: NADPH:quinone reductase

Reaction: NADPH + H+ + 2 quinone = NADP+ + 2 semiquinone

Other name(s): NADPH2:quinone reductase

Systematic name: NADPH:quinone oxidoreductase

Comments: A zinc enzyme, specific for NADPH. Catalyses the one-electron reduction of certain quinones, with the orthoquinones 1,2-naphthoquinone and 9,10-phenanthrenequinone being the best substrates [1]. Dicoumarol [cf. EC 1.6.5.2 NAD(P)H dehydrogenase (quinone)] and nitrofurantoin are competitive inhibitors with respect to the quinone substrate. The semiquinone free radical product may be non-enzymically reduced to the hydroquinone or oxidized back to quinone in the presence of O2 [1]. In some mammals the enzyme is abundant in the lens of the eye, where it is identified with the protein ζ-crystallin.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 9032-20-6

References:

1. Rao, P.V., Krishna, C.M. and Zigler, J.S., Jr. Identification and characterization of the enzymatic activity of ζ-crystallin from guinea pig lens. A novel NADPH:quinone oxidoreductase. J. Biol. Chem. 267 (1992) 96-102. [PMID: 1370456]

2. Duhaiman, A.S. Kinetic properties of camel lens ζ-crystallin. Int. J. Biochem. Cell Biol. 28 (1996) 1163-1168. [PMID: 8930141]

3. Bazzi, M.D. Interaction of camel lens ζ-crystallin with quinones: portrait of a substrate by fluorescence spectroscopy. Arch. Biochem. Biophys. 395 (2001) 185-190. [PMID: 11697855]

4. Tang, A. and Curthoys, N.P. Identification of ζ-crystallin/NADPH:quinone reductase as a renal glutaminase mRNA pH response element-binding protein. J. Biol. Chem. 276 (2001) 21375-21380. [PMID: 11294877]

[EC 1.6.5.5 created 1999]

EC 1.6.5.6

Accepted name: p-benzoquinone reductase (NADPH)

Reaction: NADPH + H+ + p-benzoquinone = NADP+ + hydroquinone

For diagram of reaction click here.

Systematic name: NADPH:p-benzoquinone oxidoreductase

Comments: Involved in the 4-nitrophenol degradation pathway in bacteria.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, UM-BBD, CAS registry number:

References:

1. Spain, J.C. and Gibson, D.T. Pathway for bioremediation of p-nitrophenol in a Moraxella sp. Appl. Environ. Microbiol. 57 (1991) 812-819.

[EC 1.6.5.6 created 2000]

EC 1.6.5.7

Accepted name: 2-hydroxy-1,4-benzoquinone reductase

Reaction: 2-hydroxy-1,4-benzoquinone + NADH + H+ = hydroxyquinol + NAD+ 2-hydroxy-1,4-benzoquinone + NADH + H+ = 1,2,4-trihydroxybenzene + NAD+

For diagram of reaction click here.

Glossary: hydroxyquinol = 1,2,4-trihydroxybenzene

Other name(s): hydroxybenzoquinone reductase; 1,2,4-trihydroxybenzene:NAD oxidoreductase; NADH:2-hydroxy-1,4-benzoquinone oxidoreductase

Systematic name: NADH:2-hydroxy-1,4-benzoquinone oxidoreductase

Comments: A flavoprotein (FMN) that differs in substrate specificity from other quinone reductases. The enzyme in Burkholderia cepacia is inducible by 2,4,5-trichlorophenoxyacetate.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, UM-BBD, CAS registry number: 214466-94-1

References:

1. Zaborina, O., Daubaras, D.L., Zago, A., Xun, L., Saido, K., Klem,T., Nikolic, D. and Chakrabarty, A.M. Novel pathway for conversion of chlorohydroxyquinol to maleylacetate in Burkholderia cepacia AC1100. J. Bacteriol. 180 (1998) 4667-4675. [PMID: 9721310]

[EC 1.6.5.7 created 2000, modified 2004]

EC 1.6.5.8

Accepted name: NADH:ubiquinone reductase (Na+-transporting)

Reaction: NADH + H+ + ubiquinone + n Na+in = NAD+ + ubiquinol + n Na+out

Other name(s): Na+-translocating NADH-quinone reductase; (Na+-NQR)

Systematic name: NADH:ubiquinone oxidoreductase (Na+-translocating)

Comments: An iron-sulfur flavoprotein, containing two covalently bound molecules of FMN, one noncovalently bound FAD, one riboflavin, and one [2Fe-2S] cluster.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:

References:

1. Beattie, P., Tan, K., Bourne, R.M., Leach, D., Rich, P.R. and Ward, F.B. Cloning and sequencing of four structural genes for the Na+-translocating NADH-ubiquinone oxidoreductase of Vibrio alginolyticus. FEBS Lett. 356 (1994) 333-338. [PMID: 7805867]

2. Nakayama, Y., Hayashi, M. and Unemoto, T. Identification of six subunits constituting Na+-translocating NADH-quinone reductase from the marine Vibrio alginolyticus. FEBS Lett. 422 (1998) 240-242. [PMID: 9490015]

3. Bogachev, A.V., Bertsova, Y.V., Barquera, B. and Verkhovsky, M.I. Sodium-dependent steps in the redox reactions of the Na+-motive NADH:quinone oxidoreductase from Vibrio harveyi. Biochemistry 40 (2001) 7318-7323. [PMID: 11401580]

4. Barquera, B., Hellwig, P., Zhou, W., Morgan, J.E., Hase, C.C., Gosink, K.K., Nilges, M., Bruesehoff, P.J., Roth, A., Lancaster, C.R. and Gennis, R.B. Purification and characterization of the recombinant Na+-translocating NADH:quinone oxidoreductase from Vibrio cholerae. Biochemistry 41 (2002) 3781-3789. [PMID: 11888296]

5. Barquera, B., Nilges, M.J., Morgan, J.E., Ramirez-Silva, L., Zhou, W. and Gennis, R.B. Mutagenesis study of the 2Fe-2S center and the FAD binding site of the Na+-translocating NADH:ubiquinone oxidoreductase from Vibrio cholerae. Biochemistry 43 (2004) 12322-12330. [PMID: 15379571]

[EC 1.6.5.8 created 2011]

EC 1.6.5.9

Accepted name: NADH:ubiquinone reductase (non-electrogenic)

Reaction: NADH + H+ + ubiquinone = NAD+ + ubiquinol

Other name(s): ubiquinone reductase (ambiguous); coenzyme Q reductase (ambiguous); dihydronicotinamide adenine dinucleotide-coenzyme Q reductase (ambiguous); DPNH-coenzyme Q reductase (ambiguous); DPNH-ubiquinone reductase (ambiguous); NADH-coenzyme Q oxidoreductase (ambiguous); NADH-coenzyme Q reductase (ambiguous); NADH-CoQ oxidoreductase (ambiguous); NADH-CoQ reductase (ambiguous); NADH-ubiquinone reductase (ambiguous); NADH-ubiquinone oxidoreductase (ambiguous); reduced nicotinamide adenine dinucleotide-coenzyme Q reductase (ambiguous); NADH-Q6 oxidoreductase (ambiguous); NADH2 dehydrogenase (ubiquinone) (ambiguous)

Systematic name: NADH:ubiquinone oxidoreductase

Comments: A flavoprotein (FAD). Occurs in mitochondria of yeast and plants, and in aerobic bacteria. Has low activity with NADPH.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number:

References:

1. Moller, I.M, and Palmer, J.M. Direct evidence for the presence of a rotenone-resistant NADH dehydrogenase on the inner surface of plant mitochondria. Physiologia Plantarum 54 (1982) 267-274.

2. de Vries, S. and Grivell, L.A. Purification and characterization of a rotenone-insensitive NADH:Q6 oxidoreductase from mitochondria of Saccharomyces cerevisiae. Eur. J. Biochem. 176 (1988) 377-384. [PMID: 3138118]

3. Kerscher, S.J., Okun, J.G. and Brandt, U. A single external enzyme confers alternative NADH:ubiquinone oxidoreductase activity in Yarrowia lipolytica. J. Cell Sci. 112 ( Pt 14) (1999) 2347-2354. [PMID: 10381390]

4. Rasmusson, A.G., Soole, K.L. and Elthon, T.E. Alternative NAD(P)H dehydrogenases of plant mitochondria. Annu. Rev. Plant Biol. 55 (2004) 23-39. [PMID: 15725055]

[EC 1.6.5.9 created 2011]

EC 1.6.5.10

Accepted name: NADPH dehydrogenase (quinone)

Reaction: NADPH + H+ + a quinone = NADP+ + a quinol

Other name(s): reduced nicotinamide adenine dinucleotide phosphate (quinone) dehydrogenase; NADPH oxidase; NADPH2 dehydrogenase (quinone)

Systematic name: NADPH:(quinone-acceptor) oxidoreductase

Comments: A flavoprotein [1,2]. The enzyme from Escherichia coli is specific for NADPH and is most active with quinone derivatives and ferricyanide as electron acceptors [3]. Menaquinone can act as acceptor. The enzyme from hog liver is inhibited by dicoumarol and folic acid derivatives but not by 2,4-dinitrophenol [1].

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number: 37256-37-4

References:

1. Koli, A.K., Yearby, C., Scott, W. and Donaldson, K.O. Purification and properties of three separate menadione reductases from hog liver. J. Biol. Chem. 244 (1969) 621-629. [PMID: 4388793]

2. Hayashi, M., Hasegawa, K., Oguni, Y. and Unemoto, T. Characterization of FMN-dependent NADH-quinone reductase induced by menadione in Escherichia coli. Biochim. Biophys. Acta 1035 (1990) 230-236. [PMID: 2118386]

3. Hayashi, M., Ohzeki, H., Shimada, H. and Unemoto, T. NADPH-specific quinone reductase is induced by 2-methylene-4-butyrolactone in Escherichia coli. Biochim. Biophys. Acta 1273 (1996) 165-170. [PMID: 8611590]

[EC 1.6.5.10 created 1972 as EC 1.6.99.6, transferred 2011 to EC 1.6.5.10]

EC 1.6.5.11

Accepted name: NADH dehydrogenase (quinone)

Reaction: NADH + H+ + a quinone = NAD+ + a quinol

Other name(s): reduced nicotinamide adenine dinucleotide (quinone) dehydrogenase; NADH-quinone oxidoreductase; DPNH-menadione reductase; D-diaphorase; NADH2 dehydrogenase (quinone)

Systematic name: NADH:(quinone-acceptor) oxidoreductase

Comments: Menaquinone can act as acceptor. Inhibited by AMP and 2,4-dinitrophenol but not by dicoumarol or folic acid derivatives.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:

References:

1. Koli, A.K., Yearby, C., Scott, W. and Donaldson, K.O. Purification and properties of three separate menadione reductases from hog liver. J. Biol. Chem. 244 (1969) 621-629. [PMID: 4388793]

[EC 1.6.5.11 created 1972 as EC 1.6.99.5, transferred 2015 to EC 1.6.5.11]

EC 1.6.5.12

Accepted name: demethylphylloquinone reductase

Reaction: demethylphylloquinone + NADPH + H+ = demethylphylloquinol + NADP+

Glossary: demethylphylloquinone = 2-phytyl-1,4-naphthoquinone

Other name(s): ndbB (gene name); NDC1 (gene name)

Systematic name: NADPH:demethylphylloquinone oxidoreductase

Comments: The enzyme, found in plants and cyanobacteria, is involved in the biosynthesis of phylloquinone (vitamin K1), an electron carrier associated with photosystem I. The enzyme is a type II NADPH dehydrogenase and requires a flavine adenine dinucleotide cofactor.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:

References:

1. Fatihi, A., Latimer, S., Schmollinger, S., Block, A., Dussault, P.H., Vermaas, W.F., Merchant, S.S. and Basset, G.J. A dedicated type II NADPH dehydrogenase performs the penultimate step in the biosynthesis of vitamin K1 in Synechocystis and Arabidopsis. Plant Cell 27 (2015) 1730-1741. [PMID: 26023160]

[EC 1.6.5.12 created 2015]


EC 1.6.6 With a nitrogenous group as acceptor

Contents

EC 1.6.6.1 now EC 1.7.1.1
EC 1.6.6.2 now EC 1.7.1.2
EC 1.6.6.3 now EC 1.7.1.3
EC 1.6.6.4 now EC 1.7.1.4
EC 1.6.6.5 now EC 1.7.99.3
EC 1.6.6.6 now EC 1.7.1.5
EC 1.6.6.7 now EC 1.7.1.6
EC 1.6.6.8 now EC 1.7.1.7
EC 1.6.6.9 trimethylamine-N-oxide reductase
EC 1.6.6.10 now EC 1.7.1.9
EC 1.6.6.11 now EC 1.7.1.10
EC 1.6.6.12 now EC 1.7.1.11
EC 1.6.6.13 now EC 1.7.1.12


[EC 1.6.6.1 Transferred entry: now EC 1.7.1.1, nitrate reductase (NADH) (EC 1.6.6.1 created 1961, deleted 2002)]

[EC 1.6.6.2 Transferred entry: now EC 1.7.1.2, nitrate reductase [NAD(P)H] (EC 1.6.6.2 created 1961, deleted 2002)]

[EC 1.6.6.3 Transferred entry: now EC 1.7.1.3, nitrate reductase (NADPH) (EC 1.6.6.3 created 1961, deleted 2002)]

[EC 1.6.6.4 Transferred entry: now EC 1.7.1.4, nitrite reductase [NAD(P)H] (EC 1.6.6.4 created 1961, deleted 2002)]

[EC 1.6.6.5 Transferred entry: now EC 1.7.99.3 nitrite reductase (EC 1.6.6.5 created 1961, deleted 1964)]

[EC 1.6.6.6 Transferred entry: now EC 1.7.1.5, hyponitrite reductase (EC 1.6.6.6 created 1961, deleted 2002)]

[EC 1.6.6.7 Transferred entry: now EC 1.7.1.6, azobenzene reductase (EC 1.6.6.7 created 1961, deleted 2002)]

[EC 1.6.6.8 Transferred entry: now EC 1.7.1.7, GMP reductase (EC 1.6.6.8 created 1965, deleted 2002)]

EC 1.6.6.9

Accepted name: trimethylamine-N-oxide reductase

Reaction: NADH + H+ + trimethylamine N-oxide = NAD+ + trimethylamine + H2O

Other name(s): trimethylamine N-oxide reductase; trimethylamine oxide reductase; TMAO reductase; TOR

Systematic name: NADH:trimethylamine-N-oxide oxidoreductase

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, UM-BBD, CAS registry number: 37256-34-1

References:

1. Unemoto, T., Hayashi, M., Miyaki, K. and Hayashi, M. Intracellular localization and properties of trimethylamine-N-oxide reductase in Vibrio parahaemolyticus. Biochim. Biophys. Acta 110 (1965) 319-328. [PMID: 4286289]

[EC 1.6.6.9 created 1972]

[EC 1.6.6.10 Transferred entry: now EC 1.7.1.9, nitroquinoline-N-oxide reductase (EC 1.6.6.10 created 1972, deleted 2002)]

[EC 1.6.6.11 Transferred entry: now EC 1.7.1.10, hydroxylamine reductase (NADH) (EC 1.6.6.11 created 1972, deleted 2002)]

[EC 1.6.6.12 Transferred entry: now EC 1.7.1.11, 4-(dimethylamino)phenylazoxybenzene reductase (EC 1.6.6.12 created 1989, deleted 2002)]

[EC 1.6.6.13 Transferred entry: now EC 1.7.1.12, N-hydroxy-2-acetamidofluorene reductase (EC 1.6.6.13 created 1989, deleted 2002)]


EC 1.6.7 With a iron-sulfur protein as acceptor

[EC 1.6.7.1 Transferred entry: now EC 1.18.1.2 ferredoxin-NADP+ reductase (EC 1.6.7.1 created 1972, deleted 1978)]

[EC 1.6.7.2 Transferred entry: now EC 1.18.1.1 rubredoxin-NAD+ reductase (EC 1.6.7.2 created 1972, deleted 1978)]


EC 1.6.8 With a flavin as acceptor

Contents

EC 1.6.8.1 now EC 1.5.1.29
EC 1.6.8.2 now EC 1.5.1.30


[EC 1.6.8.1 Transferred entry: now EC 1.5.1.29, FMN reductase (EC 1.6.8.1 created 1981, deleted 2002)]

[EC 1.6.8.2 Transferred entry: now EC 1.5.1.30, flavin reductase (EC 1.6.8.2 created 1982, deleted 2002)]


EC 1.6.99 With unknown physiological acceptors

Contents

EC 1.6.99.1 NADPH dehydrogenase
EC 1.6.99.2 now EC 1.6.5.2
EC 1.6.99.3 NADH dehydrogenase
EC 1.6.99.4 now EC 1.18.1.2
EC 1.6.99.5 now EC 1.6.5.11
EC 1.6.99.6 now EC 1.6.5.10
EC 1.6.99.7 now EC 1.5.1.34
EC 1.6.99.8 now EC 1.16.1.3
EC 1.6.99.9 now EC 1.16.1.4
EC 1.6.99.10 deleted, included in EC 1.6.99.7
EC 1.6.99.11 now EC 1.16.1.5
EC 1.6.99.12 now EC 1.16.1.6
EC 1.6.99.13 now EC 1.16.1.7


EC 1.6.99.1

Accepted name: NADPH dehydrogenase

Reaction: NADPH + H+ + acceptor = NADP+ + reduced acceptor

Other name(s): NADPH2 diaphorase; NADPH diaphorase; OYE; diaphorase; dihydronicotinamide adenine dinucleotide phosphate dehydrogenase; NADPH-dehydrogenase; NADPH-diaphorase; NADPH2-dehydrogenase; old yellow enzyme; reduced nicotinamide adenine dinucleotide phosphate dehydrogenase; TPNH dehydrogenase; TPNH-diaphorase; triphosphopyridine diaphorase; triphosphopyridine nucleotide diaphorase; NADPH2 dehydrogenase; NADPH:(acceptor) oxidoreductase

Systematic name: NADPH:acceptor oxidoreductase

Comments: A flavoprotein (FMN in yeast, FAD in plants).

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, UM-BBD, CAS registry number: 9001-68-7

References:

1. Åkesson, Å., Ehrenberg, A. and Theorell, H. Old yellow enzyme. In: Boyer, P.D., Lardy, H. and Myrbäck, K. (Ed.), The Enzymes, 2nd ed., vol. 7, Academic Press, New York, 1963, p. 477-494.

2. Avron, M. and Jagendorf, A.T. Some further investigations on chloroplast TPNH diaphorase. Arch. Biochem. Biophys. 72 (1957) 17-24.

3. Jagendorf, A.T. Chloroplast TPNH diaphorase. Methods Enzymol. 6 (1963) 430-434.

4. Theorell, H. Das gelbe Oxydationsferment. Biochem. Z. 278 (1935) 263-290.

5. Theorell, H. and Åkesson, Å. Molecular weight and FMN content of crystalline "old yellow enzyme". Arch. Biochem. Biophys. 65 (1956) 439-448.

[EC 1.6.99.1 created 1961, modified 1976]

[EC 1.6.99.2 Transferred entry: now EC 1.6.5.2, NAD(P)H dehydrogenase (quinone). The enzyme was erroneously transferred from this sub-subclass in 1965 (EC 1.6.99.2 created 1961 as EC 1.6.5.2, transferred 1965 to EC 1.6.99.2, deleted 2005)]

EC 1.6.99.3

Accepted name: NADH dehydrogenase

Reaction: NADH + H+ + acceptor = NAD+ + reduced acceptor

Other name(s): cytochrome c reductase; type 1 dehydrogenase; β-NADH dehydrogenase dinucleotide; diaphorase; dihydrocodehydrogenase I dehydrogenase; dihydronicotinamide adenine dinucleotide dehydrogenase; diphosphopyridine diaphorase; DPNH diaphorase; NADH diaphorase; NADH hydrogenase; NADH oxidoreductase; NADH-menadione oxidoreductase; reduced diphosphopyridine nucleotide diaphorase; NADH:cytochrome c oxidoreductase; NADH2 dehydrogenase; NADH:(acceptor) oxidoreductase

Systematic name: NADH:acceptor oxidoreductase

Comments: A flavoprotein containing iron-sulfur centres. After preparations have been subjected to certain treatments, cytochrome c may act as an acceptor. Under normal conditions, two protons are extruded from the cytoplasm or the intramitochondrial or stromal compartment. Formerly EC 1.6.2.1; present in a mitochondrial complex as EC 1.6.5.3 NADH dehydrogenase (ubiquinone).

Links to other databases: BRENDA, EXPASY, GTD, KEGG, Metacyc, PDB, CAS registry number: 9079-67-8

References:

1. Adachi, K. and Okuyama, T. Study on the reduced pyridine nucleotide dehydrogenase of bovine erythrocytes. I. Crystallization and properties of the reduced pyridine nucleotide dehydrogenase of bovine erythrocytes. Biochim. Biophys. Acta 268 (1972) 629-637. [PMID: 4402556]

2. Hatefi, Y., Ragan, C.I. and Galante, Y.M. The enzymes and the enzyme complexes of the mitochondrial oxidative phosphorylation system. In: Martonosi, A.N. (Ed.), The Enzymes of Biological Membranes, 2nd ed., vol. 4, Wiley, New York, 1985, p. 1-70.

3. Hochstein, L.I. and Dalton, B.P. Studies of a halophilic NADH dehydrogenase. I. Purification and properties of the enzyme. Biochim. Biophys. Acta 302 (1973) 216-228. [PMID: 4144655]

4. Kaniuga, Z. The transformation of mitochondrial NADH dehydrogenase into NADH:Cytochrome c oxidoreductase. Biochim. Biophys. Acta 73 (1963) 550-564.

[EC 1.6.99.3 created 1961 as EC 1.6.2.1, transferred 1965 to EC 1.6.99.3]

[EC 1.6.99.4 Transferred entry: now EC 1.18.1.2 ferredoxin-NADP+ reductase (EC 1.6.99.4 created 1965, deleted 1972)]

[EC 1.6.99.5 Transferred entry: NADH dehydrogenase (quinone). Transferred to EC 1.6.5.11, NADH dehydrogenase (quinone) (EC 1.6.99.5 created 1972, deleted 2014)]

[EC 1.6.99.6 Transferred entry: Transferred to EC 1.6.5.10, NADPH dehydrogenase (quinone) (EC 1.6.99.6 created 1972, deleted 2011)]

[EC 1.6.99.7 Transferred entry: now EC 1.5.1.34 6,7-dihydropteridine reductase. (EC 1.6.99.7 created 1972, modified 1981 (EC 1.6.99.10 created 1978, incorporated 1981), deleted 2003)]

[EC 1.6.99.8 Transferred entry: now EC 1.16.1.3, aquacobalamin reductase (EC 1.6.99.8 created 1972, deleted 2002)]

[EC 1.6.99.9 Transferred entry: now EC 1.16.1.4, cob(II)alamin reductase (EC 1.6.99.9 created 1972, deleted 2002)]

EC 1.6.99.10 Deleted entry: now included with EC 1.5.1.34, 6,7-dihydropteridine reductase [EC 1.6.99.10 created 1978, deleted 1981]

[EC 1.6.99.11 Transferred entry: now EC 1.16.1.5, aquacobalamin reductase (NADPH) (EC 1.6.99.11 created 1989, deleted 2002)]

[EC 1.6.99.12 Transferred entry: now EC 1.16.1.6, cyanocobalamin reductase (cyanide-eliminating) (EC 1.6.99.12 created 1989, deleted 2002)]

[EC 1.6.99.13 Transferred entry: now EC 1.16.1.7, ferric-chelate reductase (EC 1.6.99.13 created 1992, deleted 2002)]


Continued with EC 1.7 and EC 1.8
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