Prochiral Sulfoxidation as a Probe for Multiple Forms of the Microsomal Flavin-Containing Monooxygenase: Studies with Rabbit FMO1, FMO2, FMO3, and FMO5 Expressed in Escherichia coli

Multiple forms of the microsomal flavin-containing monooxygenase (FMO) exist in rabbit tissues. In order to better understand the catalytic properties of these isoforms, we have expressed rabbit FMO1, FMO2, FMO3, and FMO5 in Escherichia coli and examined their kinetic parameters and prochiral selectivities for the sulfoxidation of methyl-, ethyl-, n-propyl-, and n-butyl-substituted p-tolyl sulfides. FMO1 and FMO2 exhibited high affinities for these substrates (Km