Topic summary
Mixed-function oxidase
Mixed-function oxidase refers to a family of oxidaseenzymes that catalyze the splitting of oxygen (O2) into water and an O atom, which attaches to substrate. A major example is cytochrome P450, a large family of enzymes. The term "mixed function oxidase" is seldom used among enzymologists.
Oxidase is a general name for enzymes that catalyze oxidations in which molecular oxygen (O2) is the electron acceptor but oxygen atoms do not appear in the oxidized product. Often, oxygen is reduced to either water (cytochrome oxidase of the mitochondrialelectron transfer chain) or hydrogen peroxide (dehydrogenation of fatty acyl-CoA in peroxisomes). Most of the oxidases are flavoproteins. By contrast, "mixed-function oxidase" behaves only partially as an oxidase (producing water from O2) but partially for some other process such as hydroxylation or desaturation of fatty acyl-CoA in vertebrates is an example of the mixed-function oxidase reaction. In the process, saturated fatty acyl-CoA and NADPH are oxidized by molecular oxygen (O2) to produce monounsaturated fatty acyl-CoA, NADP and 2 molecules of water.