MAOB(MONOAMINE OXIDASE B),also called MAO, BRAIN, AMINE OXIDASE (FLAVIN-CONTAINING) B, is a protein that in humans is encoded by the MAOB gene.MAOB is a member of the flavin monoamine oxidase family. And it is mapped on Xp11.3.MAOB catalyzes the oxidative deamination of biogenic and xenobiotic amines and plays an important role in the metabolism of neuroactive and vasoactive amines in the central nervous system and peripheral tissues. This protein preferentially degrades benzylamine and phenylethylamine. Like MAOA, it also degrades dopamine. MAO-B is involved in the breakdown of dopamine, a neurotransmitter implicated in reinforcing and motivating behaviors as well as movement. MAO-B inhibition is, therefore, associated with enhanced activity of dopamine, as well as with decreased production of hydrogen peroxide, a source of reactive oxygen species.