Inbiochemistry, anoxidoreductase is anenzyme that catalyzes the transfer ofelectrons from one molecule, thereductant, also called theelectron donor, to another, theoxidant, also called theelectron acceptor. This group of enzymes usually utilizesNADP+ orNAD+ ascofactors.[1][2] Transmembrane oxidoreductases createelectron transport chains in bacteria,chloroplasts andmitochondria, including respiratory complexesI,II andIII. Some others can associate withbiological membranes asperipheral membrane proteins or be anchored to the membranes through a singletransmembrane 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, theredox reactions are sometimes more difficult to see, such as this reaction fromglycolysis:
In this reaction, NAD+ is the oxidant (electron acceptor), andglyceraldehyde-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 asEC 1 in theEC number classification of enzymes. Oxidoreductases can be further classified into 21 subclasses:
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