A novel method for direct electrochemistry of a thermoacidophilic cytochrome P450

Direct electron transfer of cytochrome P450 from the thermoacidophilic crenarchaeon, Sulfolobus tokodaii strain 7, (P450st) entrapped onto the surface of a plastic formed carbon electrode in poly(ethylene oxide) (PEO) containing 0.5 M KCl was achieved. The formal potential for wild-type P450st is −103 mV (vs. Ag wire). Thermophilic P450st was modified with PEO having an average molecular weight of 2000 (PEO2000) to increase its stability in PEO solvent. The P450st enzyme was dissolved in several organic media and PEO oligomers after the modification. Resonance Raman spectra revealed no effects of chemical modification with PEO2000 and PEO solvent on the heme structure of P450st. The electrochemical responses of PEO2000-modified P450st in PEO solvent were well-defined and stable compared with those of wild-type P450st. Voltammetry of the modified protein on the surface of a plastic formed carbon electrode in PEO solvent showed a FeIII/FeII potential at −114 mV vs. Ag wire, which is similar to that of wild-type P450st.