The flavin-containing monooxygenase (FMO) protein family specializes in the oxidation of xeno-substrates in order to facilitate the excretion of these compounds from living organisms.[1] These enzymes can oxidize a wide array of heteroatoms, particularly soft nucleophiles, such as amines, sulfides, and phosphites. This reaction requires an oxygen, an NADPHcofactor, and an FADprosthetic group.[2][3][4] FMOs share several structural features, such as a NADPH binding domain, FAD binding domain, and a conserved arginine residue present in the active site. Recently, FMO enzymes have received a great deal of attention from the pharmaceutical industry both as a drug target for various diseases and as a means to metabolize pro-drug compounds into active pharmaceuticals.[5] These monooxygenases are often misclassified because they share activity profiles similar to those of cytochrome P450 (CYP450), which is the major contributor to oxidative xenobiotic metabolism. However, a key difference between the two enzymes lies in how they proceed to oxidize their respective substrates; CYP enzymes make use of an oxygenated heme prosthetic group, while the FMO family utilizes FAD to oxidize its substrates.
^Cashman JR (March 1995). "Structural and catalytic properties of the mammalian flavin-containing monooxygenase". Chemical Research in Toxicology. 8 (2): 166–81. doi:10.1021/tx00044a001. PMID7766799.
