Electrochemical investigations of fungal cytochrome P450

The electrochemical investigations of fungal (Aspergillus terreus MTCC 6324) cytochrome P450 monooxygenase (CYP) (EC 1.14.14.1) immobilized on multi-walled carbon nanotubes–Nafion®–polyethyleneimine (MWCNT-NF/PEI) modified glassy carbon electrode (GCE) were carried out to understand the electrochemistry of the CYP and its application potential in electrochemical-based devices. In deoxygenated condition, the formal potential for Fe(III)/Fe(II) redox couple of CYP was about −0.53 V (vs. Ag/AgCl reference electrode, pH 8). A positive shift in the redox potential of the bioelectrode to −0.475 V was observed in the presence of oxygen and substrate. The electrocatalytic activity towards n-hexadecane and inhibition with piperonyl butoxide (PBO) confirmed the involvement of Fe(III/II) system of CYP in the redox process. The current response increased linearly from 1 μM to 100 μM of n-hexadecane with detection limit 0.1 μM. The IC50 for PBO was 2.7 μM. The surface coverage of CYP immobilized on MWCNT-NF/PEI modified GCE was approximately 3.45 × 10−10 mol cm−2. The electron transfer rate constant (ks) was 1.0 ± 0.2 s−1, indicating facilitation of the electron transfer between CYP and GCE.

► Direct electrochemistry of a CYP from Aspergillus terreus is established using MWCNT-NF/PEI modified GCE.
► Involvement of Fe(III)/Fe(II) of CYP in the bioelectrocatalysis is confirmed using CYP inhibitor.
► A +Ve shift in the CYP potential in presence of O2 and substrate supports the thermodynamic switch in the catalysis.
► The potential of the CYP and its fabrication procedure for bioelectronic devices established.