TABLE 1.
Different types of oxidoreductases.
| Type | Characteristics |
| Oxidases | Catalyze direct transfer of hydrogen from substrates to oxygen. producing water (or in some cases hydrogen peroxide) |
| Named as “Donor” oxidase with O2 as the acceptor | |
| Examples: Bilirubin oxidase (EC 1.3.3.5), Monoamine oxidases (MAO) (EC 1.4.3.4), Laccases (EC 1.10.3.2) | |
| General reaction: | |
| Substrate(reduced) + O2 = Product(oxidized) + H2O | |
| Dehydrogenases | Catalyze the oxidation of substrates by transferring one or more hydride ions to an acceptor substrate. Named as “donor” dehydrogenase |
| Examples: Alcohol dehydrogenase (EC 1.1.1.1), Glutamate dehydrogenases (EC 1.4.1), Hydrogenases (EC 1.12) | |
| General reaction: | |
| Substrate1(oxidized) + Substrate2(reduced) = Product1(reduced) + Product2(oxidized) + H+ |
|
| Reductases | Catalyze the reduction of a substrate. Named as “acceptor” reductase |
| Examples: Glutathione-disulfide reductase (EC 1.8.1.7) | |
| General reaction: | |
| Substate + Electron acceptor = Product + Reduced acceptor | |
| Dismutases | Catalyzes a dismutation reaction (or disproportionation) where one compound of intermediate oxidation state converts to two compounds, one of higher and one of lower oxidation states |
| Example: Catalase (EC 1.11.1.6), Superoxide dismutase (EC 1.15.1.1) | |
| General Reaction: | |
| 2 Superoxide + 2 H+ = O2 + H2O2 | |
| Oxygenases | Catalyze the addition of oxygen into a substrate. They are further classified into: |
| Dioxygenase (true oxygenases): These enzymes incorporate both atoms of molecular oxygen (O2) into the product(s) of the reaction | |
| Examples: Heme oxygenases (EC 1.14.99.3) | |
| Mono-oxygenases (pseudo-oxygenases; hydroxylases; mixed function oxygenases). These enzymes incorporate one oxygen atom as a hydroxyl group into the substrate, while the other oxygen atom is reduced to water | |
| Examples: cytochrome P450 enzymes (E.C. 1.14) | |
| General Reaction: | |
| Substrate(reduced) + O2 = Product(oxidized) |