Enzyme Electrochemistry — Biocatalysis on an Electrode

Paul V. Bernhardt

doi:10.1071/CH05340

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Enzyme Electrochemistry — Biocatalysis on an Electrode

Paul V. Bernhardt ^A

+ Author Affiliations

- Author Affiliations

^A Centre for Metals in Biology, Department of Chemistry, University of Queensland, Brisbane QLD 4072, Australia. Email: p.bernhardt@uq.edu.au

Paul Bernhardt obtained his B.Sc.(Hons) in 1987 and Ph.D. in 1991 from the University of Newcastle. Following postdoctoral fellowships at the University of Basel (1991–1992) and the Australian National University (1993–1994) he joined the Chemistry Department at the University of Queensland in 1994. He is currently Associate Professor in Chemistry. His research interests include protein electrochemistry, bioinorganic chemistry, mixed valence compounds, and macrocyclic chemistry. He is the Director of the University of Queensland's Centre for Metals in Biology.

Australian Journal of Chemistry 59(4) 233-256 https://doi.org/10.1071/CH05340
Submitted: 17 December 2005 Accepted: 6 March 2006 Published: 1 May 2006

Abstract

Oxidoreductase enzymes catalyze single- or multi-electron reduction/oxidation reactions of small molecule inorganic or organic substrates, and they are integral to a wide variety of biological processes including respiration, energy production, biosynthesis, metabolism, and detoxification. All redox enzymes require a natural redox partner such as an electron-transfer protein (e.g. cytochrome, ferredoxin, flavoprotein) or a small molecule cosubstrate (e.g. NAD(P)H, dioxygen) to sustain catalysis, in effect to balance the substrate/product redox half-reaction. In principle, the natural electron-transfer partner may be replaced by an electrochemical working electrode. One of the great strengths of this approach is that the rate of catalysis (equivalent to the observed electrochemical current) may be probed as a function of applied potential through linear sweep and cyclic voltammetry, and insight to the overall catalytic mechanism may be gained by a systematic electrochemical study coupled with theoretical analysis. In this review, the various approaches to enzyme electrochemistry will be discussed, including direct and indirect (mediated) experiments, and a brief coverage of the theory relevant to these techniques will be presented. The importance of immobilizing enzymes on the electrode surface will be presented and the variety of ways that this may be done will be reviewed. The importance of chemical modification of the electrode surface in ensuring an environment conducive to a stable and active enzyme capable of functioning natively will be illustrated.

Fundamental research into electrochemically driven enzyme catalysis has led to some remarkable practical applications. The glucose oxidase enzyme electrode is a spectacularly successful application of enzyme electrochemistry. Biosensors based on this technology are used worldwide by sufferers of diabetes to provide rapid and accurate analysis of blood glucose concentrations. Other applications of enzyme electrochemistry are in the sensing of macromolecular complexation events such as antigen–antibody binding and DNA hybridization. The review will include a selection of enzymes that have been successfully investigated by electrochemistry and, where appropriate, discuss their development towards practical biotechnological applications.

References

^* Fast sweep rates result merely in the typical peak-shaped transient cyclic voltammetric redox response of the mediator.

^† In the case of mediated enzyme electrochemistry, both E ₁ and E ₂ are hidden by the mediator.

Enzyme Electrochemistry — Biocatalysis on an Electrode

Abstract

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