Amine oxidase [flavin-containing] B

Amine oxidase [flavin-containing] B (MAOB) is a flavin-dependent enzyme that catalyzes the oxidative deamination of primary and secondary amines, including neurotransmitters and the neurotoxin MPTP, generating hydrogen peroxide as a byproduct (UniProt: P27338). The enzyme preferentially degrades benzylamine and phenylethylamine and plays a central role in metabolizing neuroactive and vasoactive amines throughout the central and peripheral nervous systems.

MAOB is widely expressed and participates in monoamine catabolism, a fundamental process in neurochemical homeostasis. Its activity is relevant to multiple neuropsychiatric and neurodegenerative conditions given the importance of amine metabolism in brain function (UniProt: P27338).

MAOB is upregulated in Alzheimer's Disease brain tissue. Post-mortem AD brain samples showed increased MAOB abundance compared to age-matched controls across multiple subcellular fractions, with a mean log2 fold-change of 1.35 (Chaparral AD proteomics). This elevation may reflect increased oxidative stress or neuroinflammatory processes characteristic of AD pathology, as elevated MAOB activity would generate additional reactive oxygen species through amine oxidation.