Functional activity of the mouse flavin-containing monooxygenase forms 1, 3, and 5.
Three functional mouse flavin-containing monooxygenases (mFMOs) (i.e., mFMO1, mFMO3, and mFMO5) have been reported to be the major FMOs present in mouse liver. To examine the biochemical features of these enzymes, recombinant enzymes were expressed as maltose-binding protein fusion proteins (i.e., MBP-mFMO1, MBP-mFMO3, and MBP-mFMO5) in Escherichia coli and isolated and purified with affinity chromatography. The substrate specificity of these three mouse hepatic FMO enzymes were examined using a variety of substrates, including mercaptoimidazole, trimethylamine, S-methyl esonarimod, and an analog thereof, and a series of 10-(N,N-dimethylaminoalkyl)-2-(trifluoromethyl)phenothiazine analogs. The kinetic parameters of the three mouse FMOs for these substrates were compared in an attempt to explore substrate structure--function relationships specific for each mFMO. Utilizing a common phenothiazine substrate for all three enzymes, we compared the pH dependence for the recombinant enzymes under similar conditions. In addition, thermal stability for mFMO1, mFMO3, and mFMO5 enzymes was examined in the presence and absence of NADPH. The results revealed unique features for mFMO5, suggesting possible impact on the functional significance of this abundantly expressed FMO5 isoform in both human and mouse liver.
Zhang
Jun
J
Human BioMolecular Research Institute, 5310 Eastgate Mall, San Diego, CA 92121, USA.
Cerny
Matt A
MA
Lawson
Matt
M
Mosadeghi
Ruzbeh
R
Cashman
John R
JR
D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D002846:Chromatography, Affinity; D003001:Cloning, Molecular; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000201:enzymology / Q000378:metabolism; D008297:Male; D058619:Maltose-Binding Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D015394:Molecular Structure; D009249:NADP / Q000378:metabolism; D010105:Oxygenases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000302:isolation & purification / Q000378:metabolism; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
D002352:Carrier Proteins; D007527:Isoenzymes; D058619:Maltose-Binding Proteins; D011993:Recombinant Fusion Proteins; D009249:NADP; D010105:Oxygenases; C020066:dimethylaniline monooxygenase (N-oxide forming)