(Science: enzyme) That catalyses the incorporation of the oxygen of molecular oxygen into organic substrates. Dioxygenases (oxygen transferases) catalyse introduction of both atoms of molecular oxygen, monoxygenases (mixed function oxygenases) introduce one atom, the other becomes reduced to water, so that these enzymes require a second substrate, acting as oxygen donor. Both types are used by bacteria in degradation of aromatic compounds. Dioxygenases all contain iron, for example tryp 2, 3 dioxygenase.
Examples of mono oxygenases are the enzymes that hydroxylate proline and lysine of collagen, using ketoglutarate.