Mechanistic Insights into Voltage-Driven Biocatalysis of a Cytochrome P450 Bactosomal Film on a Self-Assembled Monolayer

Simple construction of biocatalytically active films of cytochrome P450 (CYP) bactosomes is quite useful for low-cost, stereoselective, and nicotinamide adenine dinucleotide phosphate hydride-free drug metabolism assays, biosensing, and biocatalytic applications. We report here real-time monitoring of the formation of biocatalytically active films of membrane-bound human CYP 2C9 or 3A4 expressed with CYP reductase (CPR) in Escherichia coli (so-called bactosomes) on a cysteamine self-assembled monolayer of gold-infused quartz crystals. The CYP 2C9+CPR-containing bactosomes exhibited oxygen reduction currents and metabolite yields greater than those of the CYP 3A4+CPR film. The electrocatalytic property correlated with the greater levels of CPR activity and the amount of CYP 2C9 in the CYP 2C9+CPR bactosomes than in the CYP 3A4+CPR bactosomes. The electron mediating role of CPR in the CYP 2C9 bactosomal film (E°′ = −450 mV vs Ag/AgCl) toward electrocatalytic oxygen reduction and hydroxylation of diclofenac ...