Oxidoreductase

In biochemistry, an oxidoreductase is an enzyme that catalyzes the transfer of electrons from one molecule, the reductant, also called the electron donor, to another, the oxidant, also called the electron acceptor. This group of enzymes usually utilizes NADP or NAD+ as cofactors.^[1]^[2]

Reactions

For example, an enzyme that catalyzed this reaction would be an oxidoreductase:

A^– + B → A + B^–

In this example, A is the reductant (electron donor) and B is the oxidant (electron acceptor).

In biochemical reactions, the redox reactions are sometimes more difficult to see, such as this reaction from glycolysis:

P_i + glyceraldehyde-3-phosphate + NAD⁺ → NADH + H⁺ + 1,3-bisphosphoglycerate

In this reaction, NAD⁺ is the oxidant (electron acceptor), and glyceraldehyde-3-phosphate is the reductant (electron donor).

Nomenclature

Proper names of oxidoreductases are formed as "donor:acceptor oxidoreductase"; however, other names are much more common. The common name is "donor dehydrogenase" when possible, such as glyceraldehyde-3-phosphate dehydrogenase for the second reaction above. Common names are also sometimes formed as "acceptor reductase", such as NAD⁺ reductase. "Donor oxidase" is a special case where O₂ is the acceptor.

Classification

Oxidoreductases are classified as EC 1 in the EC number classification of enzymes. Oxidoreductases can be further classified into 22 subclasses:

EC 1.1 includes oxidoreductases that act on the CH-OH group of donors (alcohol oxidoreductases)
EC 1.2 includes oxidoreductases that act on the aldehyde or oxo group of donors
EC 1.3 includes oxidoreductases that act on the CH-CH group of donors (CH-CH oxidoreductases)
EC 1.4 includes oxidoreductases that act on the CH-NH₂ group of donors (Amino acid oxidoreductases, Monoamine oxidase)
EC 1.5 includes oxidoreductases that act on CH-NH group of donors
EC 1.6 includes oxidoreductases that act on NADH or NADPH
EC 1.7 includes oxidoreductases that act on other nitrogenous compounds as donors
EC 1.8 includes oxidoreductases that act on a sulfur group of donors
EC 1.9 includes oxidoreductases that act on a heme group of donors
EC 1.10 includes oxidoreductases that act on diphenols and related substances as donors
EC 1.11 includes oxidoreductases that act on peroxide as an acceptor (peroxidases)
EC 1.12 includes oxidoreductases that act on hydrogen as donors
EC 1.13 includes oxidoreductases that act on single donors with incorporation of molecular oxygen (oxygenases)
EC 1.14 includes oxidoreductases that act on paired donors with incorporation of molecular oxygen
EC 1.15 includes oxidoreductases that act on superoxide radicals as acceptors
EC 1.16 includes oxidoreductases that oxidize metal ions
EC 1.17 includes oxidoreductases that act on CH or CH₂ groups
EC 1.18 includes oxidoreductases that act on iron-sulfur proteins as donors
EC 1.19 includes oxidoreductases that act on reduced flavodoxin as a donor
EC 1.20 includes oxidoreductases that act on phosphorus or arsenic in donors
EC 1.21 includes oxidoreductases that act on X-H and Y-H to form an X-Y bond
EC 1.97 includes other oxidoreductases

References

↑ Eric J. Toone (2006). Advances in Enzymology and Related Areas of Molecular Biology, Protein Evolution (Volume 75 ed.). Wiley-Interscience. ISBN 0471205036.
↑ Nicholas C. Price; Lewis Stevens (1999). Fundamentals of Enzymology: The Cell and Molecular Biology of Catalytic Proteins (Third ed.). USA: Oxford University Press. ISBN 019850229X.

External links

EC 1 Introduction from the Department of Chemistry at Queen Mary, University of London

Oxidoreductases: alcohol oxidoreductases (EC 1.1)

1.1.1: NAD/NADP acceptor	3-hydroxyacyl-CoA dehydrogenase 3-hydroxybutyryl-CoA dehydrogenase Alcohol dehydrogenase Aldo-keto reductase 1A1 1B1 1B10 1C1 1C3 1C4 7A2 Aldose reductase Beta-Ketoacyl ACP reductase Carbohydrate dehydrogenases Carnitine dehydrogenase D-malate dehydrogenase (decarboxylating) DXP reductoisomerase Glucose-6-phosphate dehydrogenase Glycerol-3-phosphate dehydrogenase HMG-CoA reductase IMP dehydrogenase Isocitrate dehydrogenase Lactate dehydrogenase L-threonine dehydrogenase L-xylulose reductase Malate dehydrogenase Malate dehydrogenase (decarboxylating) Malate dehydrogenase (NADP+) Malate dehydrogenase (oxaloacetate-decarboxylating) Malate dehydrogenase (oxaloacetate-decarboxylating) (NADP+) Phosphogluconate dehydrogenase Sorbitol dehydrogenase Hydroxysteroid dehydrogenase: 3 Beta 3-beta-HSD NSDHL 11 Beta HSD11B1 HSD11B2 17 Beta

1.1.2: cytochrome acceptor	D-lactate dehydrogenase (cytochrome) D-lactate dehydrogenase (cytochrome c-553) Mannitol dehydrogenase (cytochrome)

1.1.3: oxygen acceptor	Glucose oxidase L-gulonolactone oxidase Xanthine oxidase

1.1.4: disulfide as acceptor	Vitamin K epoxide reductase Vitamin-K-epoxide reductase (warfarin-insensitive)

1.1.5: quinone/similar acceptor	Malate dehydrogenase (quinone) Quinoprotein glucose dehydrogenase

1.1.99: other acceptors	Choline dehydrogenase L2HGDH

Aldehyde/oxo oxidoreductases (EC 1.2)

1.2.1: NAD or NADP	Aldehyde dehydrogenase Acetaldehyde dehydrogenase Long-chain-aldehyde dehydrogenase

1.2.2: cytochrome	Formate dehydrogenase (cytochrome)

1.2.3: oxygen	Aldehyde oxidase

1.2.4: disulfide	Oxoglutarate dehydrogenase complex Pyruvate dehydrogenase Branched-chain alpha-keto acid dehydrogenase complex BCKDHA BCKDHB DBT DLD

1.2.7: iron-sulfur protein	Pyruvate synthase

Oxidoreductases: CH–CH oxidoreductases (EC 1.3)

1.3.1: NAD/NADP acceptor	Enoyl-acyl carrier protein reductase/Enoyl ACP reductase 7-Dehydrocholesterol reductase Biliverdin reductase 2,4 Dienoyl-CoA reductase Dihydroxymethyloxo-tetrahydroquinoline dehydrogenase

1.3.3: Oxygen acceptor	Dihydroorotate dehydrogenase Coproporphyrinogen III oxidase Protoporphyrinogen oxidase Bilirubin oxidase Acyl-CoA oxidase Dihydrouracil oxidase Tetrahydroberberine oxidase Secologanin synthase Tryptophan alpha,beta-oxidase Pyrroloquinoline-quinone synthase L-galactonolactone oxidase

1.3.5: Quinone	Succinate dehydrogenase SDHA SDHB SDHC SDHD

1.3.99: Other acceptors	Fumarate reductase Butyryl-CoA dehydrogenase Acyl CoA dehydrogenase ACADSB ACADS 5α-reductase SRD5A1 SRD5A2 SRD5A3 Glutaryl-CoA dehydrogenase Isovaleryl coenzyme A dehydrogenase 3-oxo-5beta-steroid 4-dehydrogenase

CH-NH₂ oxidoreductases (EC 1.4) - primarily amino acid oxidoreductases

1.4.1: NAD/NADP acceptor	Glutamate dehydrogenase GLUD1 GLUD2 Glutamate synthase (NADPH)

1.4.3: oxygen acceptor	D-amino acid oxidase Amine oxidase (Copper-containing (Lysyl Diamine Primary-amine)) (Flavin-containing (Monoamine)))

1.4.4: disulfide acceptor	Glycine cleavage system

1.4.99: other acceptors	D-amino acid dehydrogenase Amine dehydrogenase

Oxidoreductases: CH-NH (EC 1.5)

1.5.1: NAD or NADP acceptor	Dihydrofolate reductase Saccharopine dehydrogenase Methylenetetrahydrofolate reductase

1.5.3: oxygen acceptor	Dihydrobenzophenanthridine oxidase Sarcosine oxidase Proline oxidase

1.5.5: quinone acceptor	Electron-transferring-flavoprotein dehydrogenase

1.5.99	Sarcosine dehydrogenase Cytokinin dehydrogenase

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)

Oxidoreductases: nitrogenous donor (EC 1.7)

1.7.1	GMP reductase

1.7.2	Nitrite reductase (NO-forming)

1.7.3	Urate oxidase

1.7.7	Ferredoxin—nitrite reductase

1.7.99	Hydroxylamine reductase

Oxidoreductases: sulfur oxidoreductases (EC 1.8)

1.8.1: NAD or NADP	Dihydrolipoamide dehydrogenase Glutathione reductase Thioredoxin reductase

1.8.2: cytochrome	Sulfite dehydrogenase Thiosulfate dehydrogenase

1.8.3: oxygen	Sulfite oxidase

1.8.4: disulfide	Glutathione—homocystine transhydrogenase

1.8.5: quinone	Glutathione dehydrogenase (ascorbate)

1.8.98: Other, known	CoB—CoM heterodisulfide reductase

1.8.99: Other	Sulfite reductase

Oxidoreductases: Acting on a heme group of donors (EC 1.9)

1.9.3	Cytochrome c oxidase

1.9.6	Nitrate reductase (cytochrome)

1.9.99	Iron—cytochrome-c reductase

Oxidoreductases: diphenol family (EC 1.10)

1.10.1	Trans-acenaphthene-1,2-diol dehydrogenase

1.10.2	Coenzyme Q - cytochrome c reductase

1.10.3	Catechol oxidase Laccase

1.10.99	Cytochrome b6f complex

Other	Alternative oxidase

Oxidoreductases: peroxidases (EC 1.11)

1.11.1.1-14	Catalase Cytochrome c peroxidase Eosinophil peroxidase Glutathione peroxidase GPX 1 2 3 4 5 6 7 8 Horseradish peroxidase Lactoperoxidase Myeloperoxidase Thyroid peroxidase Deiodinase Iodothyronine deiodinase Iodotyrosine deiodinase

1.11.1.15 (peroxiredoxin)	1 2 3 4 5 6

Oxidoreductases: Acting on hydrogen as donor (EC 1.12)

1.12.1	Hydrogen dehydrogenase Hydrogen dehydrogenase (NADP+) Hydrogenase (NAD+, ferredoxin)

1.12.2	Cytochrome-c3 hydrogenase

1.12.5	Hydrogen:quinone oxidoreductase

1.12.7	Ferredoxin hydrogenase

1.10.98	Coenzyme F420 hydrogenase 5,10-Methenyltetrahydromethanopterin hydrogenase Methanosarcina-phenazine hydrogenase Sulfhydrogenase

1.10.99	Hydrogenase (acceptor)

Oxidoreductases: monooxygenases (EC 1.13)

1.13.11: two atoms of oxygen	lipoxygenase: Arachidonate 5-lipoxygenase Arachidonate 12-lipoxygenase/ALOX12 Arachidonate 8-lipoxygenase Arachidonate 15-lipoxygenase/ALOX15 Linoleate 11-lipoxygenase other dioxygenase: Catechol dioxygenase Homogentisate 1,2-dioxygenase Cysteine dioxygenase 4-Hydroxyphenylpyruvate dioxygenase Indoleamine 2,3-dioxygenase Chlorite dismutase

1.13.12: one atom of oxygen	Firefly luciferase

1.13.99: other	Inositol oxygenase

Oxidoreductases: dioxygenases, including steroid hydroxylases (EC 1.14)

1.14.11: 2-oxoglutarate	Prolyl hydroxylase Lysyl hydroxylase

1.14.13: NADH or NADPH	Flavin-containing monooxygenase FMO1 FMO2 FMO3 FMO4 FMO5 Nitric oxide synthase NOS1 NOS2 NOS3 Cholesterol 7 alpha-hydroxylase Methane monooxygenase 3A4 Lanosterol 14 alpha-demethylase 24-hydroxycholesterol 7α-hydroxylase

1.14.14: reduced flavin or flavoprotein	19A1 2D6 2E1

1.14.15: reduced iron-sulfur protein	11B1 11B2 11A1

1.14.16: reduced pteridine (BH4 dependent)	Phenylalanine hydroxylase Tyrosine hydroxylase Tryptophan hydroxylase

1.14.17: reduced ascorbate	Dopamine beta-hydroxylase

1.14.18-19: other	Tyrosinase Stearoyl-CoA desaturase-1

1.14.99 - miscellaneous	Cyclooxygenase Heme oxygenase (HMOX1) Squalene monooxygenase 17A1 21A2

Other oxidoreductases (EC 1.15-1.21)

1.15: Acting on superoxide as acceptor	Superoxide dismutase SOD1 SOD2 SOD3

1.16: Oxidizing metal ions	Ceruloplasmin

1.17: Acting on CH or CH2 groups	Xanthine oxidase Ribonucleotide reductase 4-Hydroxy-3-methylbut-2-enyl diphosphate reductase

1.18: Acting on iron-sulfur proteins as donors	Nitrogenase

1.19: Acting on reduced flavodoxin as donor	Nitrogenase (flavodoxin)

1.20: Acting on phosphorus or arsenic in donors	Glutaredoxin GLRX GLRX2 GLRX3 GLRX5

1.21: Acting on X-H and Y-H to form an X-Y bond	Isopenicillin N synthase Columbamine oxidase Reticuline oxidase Sulochrin oxidase (+)-bisdechlorogeodin-forming (-)-bisdechlorogeodin-forming Aureusidin synthase Tetrahydrocannabinolic acid synthase Cannabidiolic acid synthase Dichlorochromopyrrolate synthase

Enzymes

Activity	Active site Binding site Catalytic triad Oxyanion hole Enzyme promiscuity Catalytically perfect enzyme Coenzyme Cofactor Enzyme catalysis Enzyme kinetics Lineweaver–Burk plot Michaelis–Menten kinetics

Regulation	Allosteric regulation Cooperativity Enzyme inhibitor

Classification	EC number Enzyme superfamily Enzyme family List of enzymes

Types	EC1 Oxidoreductases (list) EC2 Transferases (list) EC3 Hydrolases (list) EC4 Lyases (list) EC5 Isomerases (list) EC6 Ligases (list)

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