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] Transmembrane oxidoreductases create electron transport chains in bacteria, chloroplasts and mitochondria, including respiratory complexes I, II and III. Some others can associate with biological membranes as peripheral membrane proteins or be anchored to the membranes through a single transmembrane helix.^[3]

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.^{[citation needed]}

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 21 subclasses:

EC 1.1 includes oxidoreductases that act on the CH-OH group of donors (alcohol oxidoreductases such as methanol dehydrogenase)
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

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.
^ Superfamilies of single-pass transmembrane oxidoreductases in Membranome database

External links

Media related to Oxidoreductases at Wikimedia Commons
EC 1 Introduction from the Department of Chemistry at Queen Mary, University of London

[1] Eric J. Toone (2006). Advances in Enzymology and Related Areas of Molecular Biology, Protein Evolution (Volume 75 ed.). Wiley-Interscience. ISBN 0471205036.

[2] 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.

[3] Superfamilies of single-pass transmembrane oxidoreductases in Membranome database

[1]

[2]

[3]

v t e 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: 3β 3β-HSD NSDHL 11β 11β-HSD1 11β-HSD2 17β
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 Alcohol 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

v t e Aldehyde/oxo oxidoreductases (EC 1.2)
1.2.1: NAD or NADP	Aldehyde dehydrogenase Acetaldehyde dehydrogenase Long-chain-aldehyde dehydrogenase Mycothiol-dependent formaldehyde 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

v t e 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

v t e 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

v t e 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

Reactions

Nomenclature

Classification

See also

References

External links