Dimethylaniline monooxygenase [N-oxide-forming] 4 (FMO4)

Dimethylaniline monooxygenase [N-oxide-forming] 4 (FMO4) is a member of the flavin-containing monooxygenase family of NADPH-dependent enzymes found predominantly in the adult liver and involved in the oxidative metabolism of xenobiotics, drugs, and dietary compounds, especially those featuring nucleophilic nitrogen or sulfur centers[1][5]. It facilitates the N-oxidation of trimethylamine and similar substrates, converting them into more hydrophilic compounds for excretion[1]. FMO4 is closely related to other FMOs (such as FMO2 and FMO3) but has distinct expression and substrate preferences. It participates in cellular processes relevant to cancer progression, oxidative stress response, and calcium homeostasis (shown in model organisms)[1][2][4]. Downregulation of FMO4 is associated with cancer, and its expression profile is under investigation both as a prognostic marker and as a potential therapeutic target in oncology[4]. The family, including FMO4, can impact variability in drug metabolism and propensity for adverse drug reactions due to individual differences in gene expression and activity[3][5].

Other names

Flavin-containing monooxygenase 4Dimethylaniline oxidase 4Hepatic flavin-containing monooxygenase 4FMO 4Dimethylaniline monooxygenase [N-oxide-forming] 4FMO2 (note: FMO2 is technically a distinct family member, sometimes confused)Flavin containing monooxygenase 4

NADPH-dependent oxidation of substrates at nucleophilic heteroatom centers (N or S), generating N-oxides or S-oxides and facilitating their excretion. Stabilizes C4a-hydroperoxyflavin intermediate for oxygenation reactions.