Cytochrome P450_2D6 (CYP2D6) Bioelectrode for Fluoxetine

A bioelectrode system consisting of polyaniline (PAn)-doped glassy carbon electrode (GCE) and cytochrome P450_2D6 (CYP2D6) enzyme solution was used for the amperometric study of in vitro fluoxetine biotransformation. The PAn film was potentiostatically grown at +700 mV vs. Ag/AgCl (20°C) on a 0.071 cm² GCE and used for cyclic voltammetric (CV) measurements in phosphate buffer solution (0.1 M, pH 7.5, 0.1 M KCl) of the enzyme. The response of the CYP2D6 bioelectrode to fluoxetine was consistent with uncompetitive substrate inhibition kinetics. Apparent Michaelis-Menten constant K′_m of the CYP2D6 electrode was 3.7 μmol/L, which is within the intra-hepatic fluoxetine concentration between 2 and 7 μmol/L. Thus PAn-mediated electrochemistry can be used to observe the monooxygenation reaction of CYP2D6. K′_m is the apparent Michaelis-Menten constant and K′_i is the apparent substrate inhibition constant.