Monoamine oxidase B (MAO-B)

Monoamine oxidase B is an enzyme located on the outer mitochondrial membrane that catalyzes the oxidative deamination of various biogenic and xenobiotic amines. It plays a crucial role in regulating neurotransmitter levels—especially dopamine and phenylethylamine—in the brain and peripheral tissues. The enzyme is a dimeric flavoprotein containing a covalently bound FAD cofactor essential for its catalytic activity. Structurally, it features two hydrophobic cavities—the entrance cavity and substrate cavity—whose configuration influences inhibitor specificity. Monoamine oxidase B is an established therapeutic target for neurological disorders such as Parkinson’s disease; selective inhibitors are used clinically to increase synaptic dopamine availability. Beyond neurology, altered expression has been implicated in certain cancers such as glioma. Safety concerns include potential food-drug interactions leading to hypertensive crises when using irreversible inhibitors.[1][4][5][9]

Other names

MAOBmonoamine oxidase type Bmonoamine oxidase-bmitochondrial monoamine oxidase B

Irreversible inhibition of enzymatic activity (e.g., selegiline, rasagiline form covalent adducts with FAD cofactor)[8]; Reversible inhibition by small molecules occupying substrate/entrance cavities[8]