Bioelectronic Delivery of Electrons to Cytochrome P450 Enzymes

Abstract

Cytochrome P450s (cyt P450s) are the major oxidative enzymes in human oxidative metabolism of drugs and xenobiotic chemicals. In nature, the iron heme cyt P450s utilize oxygen and electrons delivered from NADPH by a reductase enzyme to oxidize substrates stereo- and regioselectively. Significant research has been directed toward achieving these events electrochemically. This feature article discusses the direct electrochemistry of cyt P450s in thin films, and the utilization of such films for electrochemically-driven biocatalysis. Maintaining and confirming structural integrity and catalytic activity of cyt P450s in films is an essential feature of these efforts. We highlight here our efforts to elucidate the influence of iron heme spin state and secondary structure of human cyt P450s on voltammetric and biocatalytic properties, using methodologies to quantitatively describe the dynamics of these processes in thin films. We also describe the first cyt P450/reductase films that accurately mimic the natural biocatalytic pathway, and show how they can be used with voltammetry to elucidate key mechanistic features. Such bioelectronic cyt P450 systems have high value for future drug development, toxicity screening, fundamental investigations, and chemical synthesis systems.

Continuous monitoring of Naproxen by a cytochrome P450-based electrochemical sensor

“…In CYP-biosensors, enzymes are immobilized on the electrode surface that provides the electrons needed to drive the redox reaction of the heme group of CYP, by replacing the natural redox partners (Krishnan et al, 2011a). In cyclic voltammetry the redox reaction of the heme group is recorded as reduction and oxidation current peaks.…”

Thin multicomponent films for functional enzyme devices and bioreactor particles

“…vi This research culminated in our development with Sadagopan Krishnan of the first cyt P450 films to enable electrochemical activation of the natural catalytic cycle of this important class of oxidative metabolic enzymes. vii,viii …”

Electrochemical Biosensors for Drug Analysis

“…Thus, the determination of the consumption of NADPH or O 2 can be applicable approaches to determine CYP450 activity and for drug screening. These co-substrates, however, need to be present in excess in order to avoid any rate limitation, and it is not always possible to reliably determine small fluctuations in their concentration [47,48]. Flavodoxin or cytochrome NADPHreductase (CPR) linked to the CYP450 can shuttle electrons from the electrode to (Fig.…”