In biochemistry, an oxidoreductase is an enzyme that catalyzes the transfer of electrons from one molecule (the reductant, also called the hydrogen or electron donor) to another (the oxidant, also called the hydrogen or electron acceptor). This group of enzymes usually utilizes NADP or NAD as cofactors.
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).
- Pi + 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).
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.
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
- List of enzymes
Proteins: enzymes Topics Types Oxidoreductases: alcohol oxidoreductases (EC 1.1) 1.1.1: NAD/NADP acceptor
Alcohol dehydrogenase · Aldo-keto reductase (1A1, 1B1, 1B10, 1C1, 1C3, 1C4, 7A2) · Aldose reductase · Carbohydrate dehydrogenases · Carnitine dehydrogenase · DXP reductoisomerase · Glucose-6-phosphate dehydrogenase · Glycerol-3-phosphate dehydrogenase · HMG-CoA reductase · 3-hydroxyacyl-CoA dehydrogenase · Beta-hydroxybutyryl-CoA dehydrogenase · Isocitrate dehydrogenase · IMP dehydrogenase · Β-Ketoacyl ACP reductase · Lactate dehydrogenase · Malate dehydrogenase · Phosphogluconate dehydrogenase · L-threonine dehydrogenase · L-xylulose reductase · Sorbitol dehydrogenaseHydroxysteroid dehydrogenase: 3 Beta (3-beta-HSD, NSDHL) · 11 Beta (HSD11B1, HSD11B2) · 17 Beta
1.1.2: cytochrome acceptor 1.1.3: oxygen acceptor 1.1.4: disulfide as acceptor 1.1.5: quinone/similar acceptor 1.1.99: other acceptors Aldehyde/oxo oxidoreductases (EC 1.2) 1.2.1: NAD or NADP 1.2.2: cytochrome 1.2.3: oxygen 1.2.4: disulfide 1.2.7: iron-sulfur protein Oxidoreductases: CH-CH oxidoreductases (EC 1.3) 1.3.1: NAD/NADP acceptor 1.3.3: Oxygen acceptor 1.3.5: Quinone 1.3.99: Other acceptors CH-NH2 oxidoreductases (EC 1.4) - primarily amino acid oxidoreductases 1.4.1: NAD/NADP acceptor 1.4.3: oxygen acceptor 1.4.4: disulfide acceptor 1.4.99: other acceptors Oxidoreductases: CH-NH (EC 1.5) 1.5.1: NAD or NADP acceptor 1.5.3: oxygen acceptor 1.5.5: quinone acceptor 1.5.99 Oxidoreductases: NADH or NADPH (EC 1.6) 1.6.1: NAD/NADP 1.6.2: Heme 1.6.3: Oxygen 1.6.5: Quinone or similar 1.6.6: Nitrogenous group 1.6.99: other Oxidoreductases: nitrogenous donor (EC 1.7) 1.7.1 1.7.2 1.7.3 1.7.7 1.7.99 Oxidoreductases: sulfur oxidoreductases (EC 1.8) 1.8.1: NAD or NADP 1.8.2: cytochrome 1.8.3: oxygen 1.8.4: disulfide 1.8.5: quinone 1.8.98: Other, known 1.8.99: Other Oxidoreductases: diphenol family (EC 1.10) 1.10.1 1.10.2Coenzyme Q - cytochrome c reductase 1.10.3 1.10.99 Other Oxidoreductases: peroxidases (EC 1.11) 184.108.40.206-14 220.127.116.11 (peroxiredoxin) Oxidoreductases: monooxygenases (EC 1.13) 1.13.11: two atoms of oxygenCatechol dioxygenase · Homogentisate 1,2-dioxygenase · Cysteine dioxygenase · 4-Hydroxyphenylpyruvate dioxygenase · Indoleamine 2,3-dioxygenase 1.13.12: one atom of oxygen 1.13.99: other Oxidoreductases: dioxygenases, including steroid hydroxylases (EC 1.14) 1.14.11: 2-oxoglutarate 1.14.13: NADH or NADPH 1.14.14: reduced flavin or flavoprotein 1.14.15: reduced iron-sulfur protein 1.14.16: reduced pteridine (BH4 dependent) 1.14.17: reduced ascorbate 1.14.18-19: other 1.14.99 - miscellaneous Other oxidoreductases (EC 1.15-1.18) 1.15: Acting on superoxide as acceptor 1.16: Oxidizing metal ions 1.17: Acting on CH or CH2 groups 1.18: Acting on iron-sulfur proteins as donors 1.19: Acting on reduced flavodoxin as donor 1.20: Acting on phosphorus or arsenic in donors 1.21: Acting on X-H and Y-H to form an X-Y bond
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