Engineered human flavin-containing monooxygenase 3 on gold nanoparticles electrodes

Nanosized particles of gold (AuNPs) are widely used as advanced materials for protein catalysis investigation. So far, several methods have been optimised for AuNPs fabrication with a particular effort to improve their stability in solution. In this work, we describe the electrochemical study of human flavin-containing monooxygenase isoform 3 (hFMO3) in a nanoelectrode system, based on AuNPs stabilised with didodecyldimethylammonium bromide (DDAB) on glassy carbon electrode. Much interest has been focused on the hFMO3 catalysis, due to its well known detoxifying properties. Previously we described the engineering of a soluble form of hFMO3 that has been characterised by direct electrochemistry in terms of its catalytic activity towards several drugs including tamoxifen and benzidamine (1,2). Here, we studied the electrochemistry of immobilised hFMO3 using cyclic voltammetry by comparing redox features of the protein by scanning the potential at different rates, from 10 to 120 mV/sec. Our results showed that, the presence of AuNPs improved the protein electrochemical performance in terms of peak currents and of detection stability. Interestingly, we also observed that redox parameters of the protein, such as reduction and oxidation potential, midpoint potential and peak to peak separation are affected by the presence of AuNPs in the nanostructured medium. In particular we observed a shift of the redox potentials towards more negative values due to AuNPs presence. Electrochemical characteristic of the DDAB/AuNPs immobilised hFMO3 was also confirmed by electrocatalysis followed by HPLC quantification. In conclusion, the immobilization of hFMO3 protein in DDAB stabilised AuNPs nanostructured electrodes improves the bioelectrochemical performance of the enzyme, and therefore can be employed for drug screening of this important human phase one metabolizing enzyme. (1)Sadeghi SJ et al. (2010) J Am Chem Soc. 132:458 (2)Castrignanò S et al. (2010) Anal Bioanal Chem. 398:1403