@article {Krueger693, author = {Sharon K. Krueger and Mei-Fei Yueh and Sarah R. Martin and Clifford B. Pereira and David E. Williams}, title = {Characterization of Expressed Full-Length and Truncated FMO2 from Rhesus Monkey}, volume = {29}, number = {5}, pages = {693--700}, year = {2001}, publisher = {American Society for Pharmacology and Experimental Therapeutics}, abstract = {Flavin-containing monooxygenase (FMO) metabolizes a wide variety of nitrogen, sulfur, and phosphorous-containing xenobiotics. FMO2 is highly expressed in the lung of most mammals examined, but the protein has only recently been detected in humans, presumably due to a premature stop codon at AA472 in most individuals. In this study, full-length (mFMO2-535) and 3'-truncated (mFMO2-471) monkey FMO2 protein, produced by cDNA-mediated baculovirus expression, were characterized and compared with baculovirus-expressed rabbit FMO2 (rFMO2-535). Although baculovirus-expressed mFMO2-535 had properties similar to FMO in monkey lung microsomes and had catalytic properties similar to rFMO2-535, the expressed proteins differed in a number of properties in S-oxidation assays. Both enzymes had the same pH optima (pH 9.5); however, mFMO2-535 quickly lost activity at higher pH values whereas rFMO2-535 retained the majority of its activity. Also, mFMO2-535 was significantly less stable at elevated temperatures and in the presence of cholic acid but had greater activity in the presence of magnesium. mFMO2-535 had higher apparentKm andVmax/Km values than rFMO2-535 did in N-oxygenation assays. mFMO2-471 was correctly targeted to the membrane fraction, but N- and S-oxygenation was not detected. Since the AA sequence identity of mFMO2 and human FMO2 is 97\%, our results with mFMO2-535 suggest that individuals carrying the allele encoding full-length FMO2 are likely to have in vivo FMO2 activity. Such activity could result in marked differences in the metabolism, efficacy, and/or toxicity of drugs and xenobiotics for which lung is a portal of entry or target organ. The American Society for Pharmacology and Experimental Therapeutics}, issn = {0090-9556}, URL = {https://dmd.aspetjournals.org/content/29/5/693}, eprint = {https://dmd.aspetjournals.org/content/29/5/693.full.pdf}, journal = {Drug Metabolism and Disposition} }