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. Oxygenases were discovered in 1955 simultaneously by two groups, Osamu Hayaishi from Japan and Howard S. Mason from the US. There are two types of oxygenases:Monooxygenases, or mixed function oxidase, transfer one oxygen atom to the substrate, and reduce the other oxygen atom to water.Dio… (More on Oxygenase)