Inbiochemistry, 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+orNAD+ascofactors.[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 membranesasperipheral membrane proteins or be anchored to the membranes through a single transmembrane helix.[3]
For example, an enzyme that catalyzed this reaction would be an oxidoreductase:
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:
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.[citation needed]
Oxidoreductases are classified as EC 1 in the EC number classification of enzymes. Oxidoreductases can be further classified into 21 subclasses:
Media related to Oxidoreductases at Wikimedia Commons|
Aldehyde/oxo oxidoreductases (EC 1.2)
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| 1.2.1: NADorNADP |
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| 1.2.2: cytochrome |
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| 1.2.3: oxygen |
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| 1.2.4: disulfide |
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| 1.2.7: iron–sulfur protein |
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| 1.4.1: NAD/NADP acceptor |
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| 1.4.3: oxygen acceptor |
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| 1.4.4: disulfide acceptor |
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| 1.4.99: other acceptors |
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Oxidoreductases: CH-NH (EC 1.5)
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| 1.5.1: NADorNADP acceptor |
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| 1.5.3: oxygen acceptor |
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| 1.5.5: quinone acceptor |
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| 1.5.99 |
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| 1.6.1: NAD/NADP |
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| 1.6.2: Heme |
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| 1.6.3: Oxygen |
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| 1.6.5: Quinone or similar |
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| 1.6.6: Nitrogenous group |
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| 1.6.99: other |
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Oxidoreductases: sulfur oxidoreductases (EC 1.8)
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| 1.8.1: NADorNADP |
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| 1.8.2: cytochrome |
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| 1.8.3: oxygen |
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| 1.8.4: disulfide |
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| 1.8.5: quinone |
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| 1.8.98: Other, known |
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| 1.8.99: Other |
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| 1.13.11: two atoms of oxygen |
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| 1.13.12: one atom of oxygen |
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| 1.13.99: other |
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| 1.14.11: 2-oxoglutarate |
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| 1.14.13: NADHorNADPH |
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| 1.14.14: reduced flavinorflavoprotein |
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| 1.14.15: reduced iron–sulfur protein |
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| 1.14.16: reduced pteridine (BH4 dependent) |
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| 1.14.17: reduced ascorbate |
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| 1.14.18-19: other |
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| 1.14.99 - miscellaneous |
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Other oxidoreductases (EC 1.15–1.21)
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| 1.15: Acting on superoxide as acceptor |
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| 1.16: Oxidizing metal ions |
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| 1.17: Acting on CH or CH2 groups |
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| 1.18: Acting on iron–sulfur proteins as donors |
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| 1.19: Acting on reduced flavodoxin as donor |
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| 1.20: Acting on phosphorusorarsenic in donors |
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| 1.21: Acting on X-H and Y-H to form an X-Y bond |
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