Spectroelectrochemical investigation of a flavoprotein with a flavin-modified gold electrode.

TitleSpectroelectrochemical investigation of a flavoprotein with a flavin-modified gold electrode.
Publication TypeJournal Article
Year of Publication2006
AuthorsNöll, G, Kozma, E, Grandori, R, Carey, J, Schödl, T, Hauska, G, Daub, J
Date Published2006 Feb 28
KeywordsAdsorption, Coated Materials, Biocompatible, DNA-Binding Proteins, Electrochemistry, Electrodes, Escherichia coli Proteins, Flavins, Flavoproteins, Gold, Hydrogen-Ion Concentration, Repressor Proteins, Surface Properties

<p>A flavin-modified gold electrode was developed in order to catalyze the electrochemical oxidoreduction of flavoproteins. Surface modification was carried out by a two-step procedure. In the first step a mixed self-assembled monolayer obtained by adsorption of activated and nonactivated 3,3'-dithiopropionic acid (free acid and N-succinimidyl ester) was formed, followed by the covalent attachment of a N(10)-hexylamino-alkylated flavin derivative via an amide bond in the second step. The electrochemical properties of the flavin-modified electrode are presented and discussed. The redox potential of the attached flavin was measured at various pH values and the electron-transfer rate constant between electrode and flavin was determined as k0 = 5 s(-1) independent of pH. The flavin-modified electrode was successfully applied to the electrochemical and spectroelectrochemical investigation of the flavoprotein WrbA from Escherichia coli that shows some structural similarities to flavodoxins. It is concluded that the electron transfer "electrode --> flavin --> flavoprotein" occurs by a two-step hopping mechanism where the first step is rate determining. Kinetic details are discussed. Furthermore, it turned out that, in contrast to flavodoxins, where the semiquinone state is stabilized, WrbA rapidly takes up two electrons, directly leading to the fully reduced form. The presented electrode surface modification may generally lend itself for spectroelectrochemical investigations of flavoproteins.</p>

Alternate JournalLangmuir
PubMed ID16489832