Direct Electron TransferA Favorite Electron Route for Cellobiose Dehydrogenase (CDH) from Trametes villosa. Comparison with CDH from Phanerochaete chrysosporium

Abstract

This paper presents some functional differences as well as similarities observed when comparing the newly discovered cellobiose dehydrogenase (CDH) from Trametes villosa (T.v.) with the well-characterized one from Phanerochaete chrysosporium (P.c.). The enzymes were physically adsorbed on spectrographic graphite electrodes placed in an amperometric flow through cell connected to a flow system. In the case of T.v.-CDH-modified graphite electrodes, a high direct electron transfer (DET) current was registered at the polarized electrode in the presence of the enzyme substrate reflecting a very efficient internal electron transfer (IET) process between the reduced FAD-cofactor and the oxidized heme-cofactor. In the case of P.c.-CDH-modified graphite electrodes, the DET process is not as efficient, and the current will greatly increase in the presence of a mediator (mediated electron transfer, MET). As a consequence, when comparing the two types of enzyme-modified electrodes an inverted DET/MET ratio for T.v.-CDH is shown, in comparison with P.c.-CDH. The rates of the catalytic reaction were estimated to be comparable for both enzymes, by measuring the combined DET + MET currents. The inverted DET/MET ratio for T.v.-CDH-modified electrodes might suggest that probably there is a better docking between the two domains of this enzyme and that the linker region of P.c.-CDH might have an active role in modulating the rate of the IET (by changing the interdomain distance), with respect to pH. Based on the new properties of T.v.-CDH emphasized in the present study, an analytical application of a third-generation biosensor for lactose was recently published.

A Direct Electron Transfer‐Based Glucose/Oxygen Biofuel Cell Operating in Human Serum

“…One of the most attractive electrode elements for a potentially implantable BFC is a carbon material, which is cheap, abundant and biocompatible. To design this BFC, SPGE were chosen, as such electrodes are well-characterised [30] and widely used for bioelectrochemical studies of variety of enzymes including different CDH [17,28,31,32] and BOx [20,29], on which both bioelements showed excellent DET-based bioelectrocatalysis (Figures 2 and 3).…”

“…The redox potential of the heme group, the electrochemically active domain of CtCDH acting as the electron donor to the bioanode, is not yet known. However, based on the starting potentials of glucose bioelectrooxidation, on the steady-state potentials of CtCDH-modified SPGEs in the absence and presence of glucose (Table 3), as well as on previous studies of other CtCDHs from different fungi [11,12,14,17,28,32,33], one can assume that the redox potential of the heme group is close to 150 mV versus NHE. The differences between the steady-state potentials of the MvBOx-and CtCDH-SPGEs determine the maximal open circuit potential of the BFC operating in glucose-containing PBS and human serum, i.e.…”

“…A 0.1 M PB was used as the carrier and was propelled by a Gilson peristaltic pump (Minipulse 2, Villiers-le-Bel, France) at a flow rate of 0.5 mL min -1 . A working potential of +300 mV versus Ag|AgCl was applied to the working electrode [28]. One hundred microliters of a 20 mM glucose solution in buffer were injected into the carrier stream via a LabPRO six-port Rheodyne injection valve (PR700-100-01, Rheodyne, CA, USA) and the output signal was recorded on a strip chart recorder (Kipp and Zonen, type BD111, Delft, The Netherlands).…”

The Electrically Wired Molybdenum Domain of Human Sulfite Oxidase is Bioelectrocatalytically Active

“…Also, for cellobiose dehydrogenase, differences in the optimum pH for mediated electron transfer of the catalytic domain and the direct electron transfer of the holoenzyme were observed. [35] A further consideration addresses the driving force, which increases with increasing pH, because the formal potential of the heme and Os center are less pH dependent than that of the molybdenum cofactor. [36] This makes the reaction between Moco and Os more likely at high pH.…”

Nanobiomolekulare Multiproteinarchitekturen zur Etablierung von schaltbaren Signalketten auf Elektroden

“…Diese Form der Signalkette kann durch das Einbetten zweier unterschiedlicher Biokatalysatoren, dem MultikupferEnzym Laccase (Lac) [37] und dem Multidomänen-Enzym Cellobiosedehydrogenase (CDH), [38] und dem Redoxprotein Cytochrom c (Cyt c) in eine künstliche Matrix bestehend aus carboxymodifzierten Siliciumdioxidnanopartikeln aufgebaut werden (Abbildung 1).…”