Electrochemically-driven benzo[a]pyrene metabolism via human cytochrome P450 1A1 with reductase coated nitrogen-doped graphene nano-composites

Benzo[a]pyrene (BaP), one of polycyclic aromatic hydrocarbons (PAHs), is identified as a prime carcinogen. Enzymatic metabolite of BaP diol epoxide is one of the important factors in its carcinogenic effect. Herein, cytochrome P450 1A1 modified nitrogen-doped graphene was synthesized to study the BaP metabolism with electrochemically-driven pathway. The direct and reversible electron transfer of the immobilized CYP1A1 on pyrenebutyric acid modified nitrogen-doped graphene nanocomposites was observed with an apparent electron transfer constant of 0.53s−1, and formal potential of −0.48V. With addition of BaP to an air-saturated buffer, the reduction peak current of dissolved oxygen increased, which confirmed the catalytic behavior of CYP1A1 to BaP. The Michaelis-Menten constant (Kmapp) and heterogeneous reaction rate constant of the catalytical reaction were calculated to be 25.6μM and 1.9s−1, respectively. The inhibition effects of alpha-naphthoflavone on CYP1A1 catalyze-cycle were also illustrated with the IC50 value of 1.2μM. The enzyme-induced BaP metabolism could be further demonstrated by the high performance liquid chromatography (HPLC) and gas chromatography-mass spectra (GC/MS). All these results showed that the proposed system had potential application for the development of drug discovery and the prediction of the chemicals toxicity in food and environment.