Direct Electrochemistry of Microsomal Human Flavin-containing Monooxygenases 1 and 3 on Naphthalenethiol Thin Films

Flavin-containing monooxygenases (FMOs) play an essential role in the detoxification of foreign compounds, similar to cytochrome P450. We present here the direct electrochemistry of human FMO1 or FMO3 microsomes immobilized on a naphthalenethiol (Np-S)-coated electrode. Both hFMO microsomes were successfully activated on an Np-S thin film and oxidized methyl p-tolyl sulfide through direct electron transfer. The Michaelis constants were comparable to those reported in solution phase experiments. This system, which requires no NADPH and no enzyme purification step, offers a potential method for constructing cost-effective sensors.