Electron-transfer pathways between redox enzymes and electrode surfaces: reagentless biosensors based on thiol-monolayer-bound and polypyrrole-entrapped enzymes.
Based on previous results which showed that quinohemo-protein alcohol dehydrogenase (QH-ADH) entrapped within polypyrrole is able to directly transfer electrons via the conducting polymer to the electrode surface, the electron-transfer properties of this multi-cofactor enzyme adsorbed and covalently-bound to self-assembled thiol monolayers and bare electrode surfaces has been investigated more closely. While the dissolved enzyme is able to transfer electrons to the electrode via heme c as well as via the more deeply buried PQQ (fast adsorption-chemical reaction-desorption mechanism), an orientation of adsorbed QH-ADH on hydrophobic electrode surfaces, as well as of adsorbed and covalently bound QH-ADH on negatively-charged thiol monolayers could be observed. In these cases the heme c units are pointing towards the electrode surfaces resulting in an optimised direct ET rate.
Schuhmann
W
W
Analytische Chemie-Elektroanalytik & Sensorik, Ruhr-Universität Bochum, D-44780 Bochum, Germany. woschu@anachem.ruhr-uni-bochum.de
Zimmermann
H
H
Habermüller
K
K
Laurinavicius
V
V
D000426:Alcohol Dehydrogenase / Q000737:chemistry / Q000378:metabolism*; D015374:Biosensing Techniques; D004563:Electrochemistry; D004566:Electrodes; D004579:Electron Transport; D004800:Enzymes, Immobilized; D008567:Membranes, Artificial; D010088:Oxidoreductases / Q000378:metabolism*; D013499:Surface Properties
D004800:Enzymes, Immobilized; D008567:Membranes, Artificial; D010088:Oxidoreductases; D000426:Alcohol Dehydrogenase