Exploiting the Reaction of Cytochrome C with Fructose Dehydrogenase for a Multilayer Electrode Construction

Abstract

The creation of analytical electron transfer (ET) chains based on the defined arrangement of enzymes and the redox protein cytochrome c (cyt c) on electrode surfaces represents an emerging field in bioelectronics.1,2 In this study we investigate the ET reaction of the flavin-dependent enzyme fructose dehydrogenase (FDH) with the redox protein cyt c. Two different pH optima are identified for the reaction with both proteins in solution, at acidic and neutral pH. When one reaction partner - cyt c - is immobilized on a modified gold electrode surface, ET proceeds efficiently at neutral pH which can be concluded from well shaped catalytic currents obtained in cyclic voltammograms. In addition a defined dependence on the substrate concentration is observed. In acidic media the reaction can also be verified but appears to be less efficient. This indicates that two different ET pathways between the enzyme and immobilized cyt c occur. Moreover, it is demonstrated that both partners can be assembled in a stable multilayer architecture, using the biopolymer DNA as connecting polyelectrolyte. The defined layered deposition of DNA with co-immobilized FDH and cyt c is verified by surface plasmon resonance (SPR) measurements. Prepared on electrodes, substantial catalytic currents are recorded upon addition of fructose. The response is found to be dependent on the number of layers deposited on the surface. This shows that an artificial signal chain can be constructed through multiple protein layers. Our results contribute to the better understanding of the ET-reaction between FDH and cyt c in a surface confined state, providing the basic knowledge which may be relevant for the creation of innovative fructose sensitive electrodes. 1. Lisdat, F.; Dronov, R.; Moehwald, H.; Scheller, F. W.; Kurth, D. G., Chemical Communications 2009, 274-283. 2. Feifel, S. C.; Kapp, A.; Lisdat, F., in Biosensors Based on Aptamers and Enzymes, Springer 2014, 140, 253-298.