Flavin-containing monooxygenase 1 (FMO1) (FMO1)

Flavin-containing monooxygenase 1 (FMO1) is a member of the FMO family of enzymes, which are essential for the oxidative metabolism of a wide range of xenobiotics, including therapeutic drugs, pesticides, and dietary components (UniProt, Q01740). In humans, FMO1 exhibits a unique developmental expression pattern; it is the predominant FMO isoform in the fetal liver but is largely down-regulated after birth, with significant expression remaining primarily in the adult kidney and intestine (Drug Metab Dispos, 16183778). The enzyme catalyzes the N- and S-oxidation of nucleophilic heteroatoms using NADPH and molecular oxygen, typically converting lipophilic compounds into more polar, readily excretable metabolites (NIH, PMC3113314). Beyond its role in detoxification, FMO1 is the primary enzyme responsible for the endogenous biosynthesis of taurine from hypotaurine, a process critical for osmotic regulation and cytoprotection (UniProt, Q01740). Genetic variations in the FMO1 gene, such as the FMO1*6 promoter polymorphism, can lead to significant differences in drug clearance and efficacy among individuals (PubMed, 12829732). Furthermore, emerging research suggests that FMO1 may serve as a diagnostic biomarker and potential therapeutic target in certain cancers, such as gastric cancer with peritoneal metastasis (Frontiers in Oncology, 1.2.1).

Other names

Dimethylaniline monooxygenase [N-oxide-forming] 1Dimethylaniline oxidase 1Fetal hepatic flavin-containing monooxygenase 1Trimethylamine monooxygenaseFlavin-containing monooxygenase 1 (fetal liver)

FMO1 functions as a monooxygenase that catalyzes the NADPH-dependent oxidation of nucleophilic heteroatoms (nitrogen, sulfur, phosphorus, and selenium) in various drugs and xenobiotics (UniProt, Q01740; NIH, PMC3113314). For most therapeutic agents, FMO1 acts as a metabolic enzyme that facilitates detoxification and clearance by increasing compound polarity, although it can also be involved in the bioactivation of certain pro-drugs or toxic compounds (NIH, PMC4114055).