An oxygenase is any enzyme that oxidizes a substrate by transferring the oxygen from molecular oxygen O2 (as in air) to it. The oxygenases form a class of oxidoreductases; their EC number is EC 1.13 or EC 1.14.
Most oxygenases contain either a metal, usually iron, or an organic cofactor, usually flavin. These cofactors interact with O2, leading to its transfer to substrate. [1]
Oxygenases constitute a major intracellular source of iron and carbon monoxide [2]
Two types of oxygenases are recognized:
Among the most common monooxygenases are the cytochrome P450 oxidases, responsible for breaking down numerous chemicals in the body.
Oxygenases were discovered in 1955 simultaneously by two groups, Osamu Hayaishi from Japan [4] [5] [6] and Howard S. Mason from the US. [7] [8] Hayaishi was awarded the 1986 Wolf Prize in Medicine "for the discovery of the oxygenase enzymes and elucidation of their structure and biological importance." [9]
Rieske proteins are iron–sulfur protein (ISP) components of cytochrome bc1 complexes and cytochrome b6f complexes and are responsible for electron transfer in some biological systems. John S. Rieske and co-workers first discovered the protein and in 1964 isolated an acetylated form of the bovine mitochondrial protein. In 1979 Trumpower's lab isolated the "oxidation factor" from bovine mitochondria and showed it was a reconstitutively-active form of the Rieske iron-sulfur protein
It is a unique [2Fe-2S] cluster in that one of the two Fe atoms is coordinated by two histidine residues rather than two cysteine residues. They have since been found in plants, animals, and bacteria with widely ranging electron reduction potentials from -150 to +400 mV.
Catechol 1,2- dioxygenase is an enzyme that catalyzes the oxidative ring cleavage of catechol to form cis,cis-muconic acid:
In enzymology, a salicylate 1-monooxygenase (EC 1.14.13.1) is an enzyme that catalyzes the chemical reaction
In enzymology, a steroid 11beta-monooxygenase (EC 1.14.15.4) is an enzyme that catalyzes the chemical reaction
In enzymology, a thymine dioxygenase (EC 1.14.11.6) is an enzyme that catalyzes the chemical reaction
In enzymology, a trans-cinnamate 4-monooxygenase (EC 1.14.14.91) is an enzyme that catalyzes the chemical reaction
Arginine 2-monooxygenase (EC 1.13.12.1) is an enzyme that catalyzes the chemical reaction
Ascorbate 2,3-dioxygenase (EC 1.13.11.13) is an enzyme that catalyzes the chemical reaction
Chloridazon-catechol dioxygenase (EC 1.13.11.36) is an enzyme that catalyzes the chemical reaction
In enzymology, a Cypridina-luciferin 2-monooxygenase (EC 1.13.12.6) is an enzyme that catalyzes the chemical reaction
In enzymology, a cysteamine dioxygenase (EC 1.13.11.19) is an enzyme that catalyzes the chemical reaction
In enzymology, an indole 2,3-dioxygenase (EC 1.13.11.17) is an enzyme that catalyzes the chemical reaction
In enzymology, a lactate 2-monooxygenase (EC 1.13.12.4) is an enzyme that catalyzes the chemical reaction
In enzymology, a lysine 2-monooxygenase (EC 1.13.12.2) is an enzyme that catalyzes the chemical reaction
In enzymology, a phenylalanine 2-monooxygenase (EC 1.13.12.9) is an enzyme that catalyzes the chemical reaction
In enzymology, a protocatechuate 3,4-dioxygenase (EC 1.13.11.3) is an enzyme that catalyzes the chemical reaction
In enzymology, a quercetin 2,3-dioxygenase (EC 1.13.11.24) is an enzyme that catalyzes the chemical reaction
Heme oxygenase 2 is an enzyme that in humans is encoded by the HMOX2 gene.
Dioxygenases are oxidoreductase enzymes. Aerobic life, from simple single-celled bacteria species to complex eukaryotic organisms, has evolved to depend on the oxidizing power of dioxygen in various metabolic pathways. From energetic adenosine triphosphate (ATP) generation to xenobiotic degradation, the use of dioxygen as a biological oxidant is widespread and varied in the exact mechanism of its use. Enzymes employ many different schemes to use dioxygen, and this largely depends on the substrate and reaction at hand.
Alpha-ketoglutarate-dependent hydroxylases are a major class of non-heme iron proteins that catalyse a wide range of reactions. These reactions include hydroxylation reactions, demethylations, ring expansions, ring closures, and desaturations. Functionally, the αKG-dependent hydroxylases are comparable to cytochrome P450 enzymes. Both use O2 and reducing equivalents as cosubstrates and both generate water.