Mixed function oxidase
Encyclopedia
Mixed-function oxidase is the name of a family of oxidase
enzymes that catalyze a reaction in which each of the two atoms of oxygen
in O2 is used for a different function in the reaction.
Oxidase is a general name for enzymes that catalyze oxidations in which molecular oxygen 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 mitochondrial electron transfer chain) or hydrogen peroxide
(dehydrogenation
of fatty acyl-CoA in peroxisome
s). Most of the oxidases are flavoprotein
s.
The name "mixed-function oxidase" indicates that the enzyme oxidizes two different substrate simultaneously. 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.
AH + BH2 + O2 --> AOH + B + H2O
Oxidase
An oxidase is any enzyme that catalyzes an oxidation-reduction reaction involving molecular oxygen as the electron acceptor. In these reactions, oxygen is reduced to water or hydrogen peroxide ....
enzymes that catalyze a reaction in which each of the two atoms of oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
in O2 is used for a different function in the reaction.
Oxidase is a general name for enzymes that catalyze oxidations in which molecular oxygen is the electron acceptor but oxygen atoms do not appear in the oxidized product. Often, oxygen is reduced to either water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
(cytochrome oxidase of the mitochondrial electron transfer chain) or hydrogen peroxide
Hydrogen peroxide
Hydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...
(dehydrogenation
Dehydrogenation
Dehydrogenation is a chemical reaction that involves the elimination of hydrogen . It is the reverse process of hydrogenation. Dehydrogenation reactions may be either large scale industrial processes or smaller scale laboratory procedures....
of fatty acyl-CoA in peroxisome
Peroxisome
Peroxisomes are organelles found in virtually all eukaryotic cells. They are involved in the catabolism of very long chain fatty acids, branched chain fatty acids, D-amino acids, polyamines, and biosynthesis of plasmalogens, etherphospholipids critical for the normal function of mammalian brains...
s). Most of the oxidases are flavoprotein
Flavoprotein
Flavoproteins are proteins that contain a nucleic acid derivative of riboflavin: the flavin adenine dinucleotide or flavin mononucleotide ....
s.
The name "mixed-function oxidase" indicates that the enzyme oxidizes two different substrate simultaneously. 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.
Reaction
The mixed-function oxidase reaction proceeds as follows:AH + BH2 + O2 --> AOH + B + H2O