Peroxidase as a model for reduction of tertiary amine oxides catalyzed by rat hepatic supernatant and microsomal fractions.
Rat hepatic microsomal and 100,000 g supernatant fractions catalyzed an NADH- and FMN-dependent reduction of amine oxides. Horseradish peroxidase (HRP) served as a model for the amine oxide reductase located in rat hepatic 100,000 g supernatant fraction. The HRP-catalyzed reaction displayed saturation kinetics with respect to NADH and the amine oxide substrate; however, there was an optimum concentration for FMN after which inhibition was observed at increased concentrations of FMN. The reductase in the 100,000 g hepatic supernatant fraction closely paralleled HRP-catalyzed amine oxide reduction in coenzyme requirements, sensitivity to inhibitors, and substrate specificity. Moreover, the peroxidase activity of HRP and microsomal and 100,000 g supernatant fractions correlated with the NADH- and FMN-dependent amine oxide reductase activities of these enzyme preparations. The NADH- and FMN-dependent amine oxide reductase activity in 100,000 g supernatant fractions, however, did not parallel the aldehyde oxidase activity. Thus, the results indicate that there is an amine oxide reductase in rat hepatic 100,000 g supernatant fraction with catalytic properties that are modeled well by horseradish peroxidase.
Gillespie
S G
SG
Division of Medicinal and Natural Products Chemistry, College of Pharmacy, University of Iowa, Iowa City 52242.
Duffel
M W
MW
D000588:Amines / Q000378:metabolism*; D000818:Animals; D003497:Cyclic N-Oxides / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D005486:Flavin Mononucleotide / Q000378:metabolism; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism*; D008862:Microsomes, Liver / Q000378:metabolism; D009243:NAD / Q000378:metabolism; D010544:Peroxidases / Q000378:metabolism*; D051381:Rats; D015262:Xenobiotics / Q000378:metabolism*
D000588:Amines; D003497:Cyclic N-Oxides; D015262:Xenobiotics; D009243:NAD; D005486:Flavin Mononucleotide; D010544:Peroxidases