Engineering electrode surfaces for membrane-bound redox enzymes and fluorescence spectroelectrochemistry

Seminar

Prof. Lars J. C. Jeuken

Institute of Membrane and Systems Biology, Leeds University

Title: Engineering electrode surfaces for membrane-bound redox enzymes and fluorescence spectroelectrochemistry

Lars J. C. Jeuken, Lukasz Krzeminski, Sophie A. Weiss, Nikolaos N. Daskalakis

An overwhelming number of chemical reactions in nature, both in the living cell and in the inanimate world, are redox reactions. In biology, these reactions are catalysed by redox enzymes, which play a major role in almost all metabolic processes, including photosynthesis and biochemical cycles that operate in the environment. By electrically connecting redox enzymes to metallic surfaces (electrodes), a powerful sensing platform is constructed that is able to characterise details of the catalytic mechanism using electrochemical techniques. In this presentation, the versatility of bioelectrochemistry and spectroelectrochemistry will be introduced.

In the first part of this presentation, electrodes will be discussed that have been specifically engineered to study membrane-bound redox enzymes, in particular quinone-converting enzymes. In these systems, lipid membranes are bound to the surface in an arrangement that enables the electrochemical oxidation and reduction of lipophilic quinones. This system has been used to investigate different bioenergetic aspects of cytochrome bo3, an ubiquinol oxidase from Escherichia coli. To study the proton-pumping activity of cytochrome bo3, pH sensitive dyes are encapsulated in surface-adsorbed vesicles.

In the second part of this presentation, our electrochemical methods are combined with the FluRedox principle to study a copper-containing enzyme Nitrite Reducase. The FluRedox principle is a novel method in which a fluorescent dye reports on the redox state of an enzyme, introducing the unrivalled sensitivity of fluorescence spectroscopy to redox enzymes and electrochemistry. Effects of the modified metallic electrode nearby the fluorescent dye as well as the application of electric fields will be discussed.