Essential hepatic enzyme that catalyzes the oxygenation of a wide variety of nitrogen- and sulfur-containing compounds including drugs as well as dietary compounds (PubMed:10759686, PubMed:30381441, PubMed:32156684). Plays an important role in the metabolism of trimethylamine (TMA), via the production of trimethylamine N-oxide (TMAO) metabolite (PubMed:9776311). 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 (PubMed:29981269). {ECO:0000269|PubMed:10759686, ECO:0000269|PubMed:29981269, ECO:0000269|PubMed:30381441, ECO:0000269|PubMed:32156684, ECO:0000269|PubMed:9224773, ECO:0000269|PubMed:9776311}. This is the function of FMO3 (flavin containing dimethylaniline monoxygenase 3, ENSG00000007933).