Essential hepatic enzyme that catalyzes the oxygenation of a wide variety of nitrogen- and sulfur-containing compounds including drugs as well as dietary compounds. Plays an important role in the metabolism of trimethylamine (TMA), via the production of trimethylamine N-oxide (TMAO) metabolite. TMA is generated by the action of gut microbiota using dietary precursors such as choline, choline containing compounds, betaine or L-carnitine. By regulating TMAO concentration, FMO3 directly impacts both platelet responsiveness and rate of thrombus formation. H(+) + N,N-dimethylaniline + NADPH + O2 = H2O + N,N-dimethylaniline N-oxide + NADP(+) NADPH + O2 + trimethylamine = H2O + NADP(+) + trimethylamine N-oxide fenbendazole + O2 + reduced [NADPH--hemoprotein reductase] = fenbendazole S-oxide + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] albendazole + O2 + reduced [NADPH--hemoprotein reductase] = albendazole S-oxide + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] (S)-nicotine + NADPH + O2 = H2O + NADP(+) + trans-(S)-nicotine N(1')-oxide Liver. Expression is specifically repressed in male mice after puberty, preventing trimethylamine degradation. Trimethylamine is present at high concentration in the urine of male mice after puberty and acts as an attractant. Trimethylamine is a bacterial metabolite found in some animal odors, and is a repulsive odor associated with bad breath and spoiled food for most organisms, except for M.musculus, where it acts as an attractant. Belongs to the FMO family.