Cellobiose Dehydrogenase: A Versatile Catalyst for Electrochemical Applications

Abstract

Cellobiose dehydrogenase catalyses the oxidation of aldoses--a simple reaction, a boring enzyme? No, neither for the envisaged bioelectrochemical applications nor mechanistically. The catalytic cycle of this flavocytochrome is complex and modulated by its flexible cytochrome domain, which acts as a built-in redox mediator. This intramolecular electron transfer is modulated by the pH, an adaptation to the environmental conditions encountered or created by the enzyme-producing fungi. The cytochrome domain forms the base from which electrons can jump to large terminal electron acceptors, such as redox proteins, and also enables by that path direct electron transfer from the catalytically active flavodehydrogenase domain to electrode surfaces. The application of electrochemical techniques to the elucidation of the molecular and catalytic properties of cellobiose dehydrogenase is discussed and compared to biochemical methods. The results lead to valuable insights into the function of this cellulose-bound enzyme, but also form the basis of exciting applications in biosensors, biofuel cells and bioelectrocatalysis.

Investigating Aspergillus nidulans secretome during colonisation of cork cell walls

“…Oxygen is an inhibitor of cellobiose dehydrogenase activity [71] and its availability was probably significantly higher in the cork media, when compared to that of sorghum stover (submerged culture with agitation and solid state culture, respectively).…”

Mediated electron transfer of cellobiose dehydrogenase and glucose oxidase at osmium polymer-modified nanoporous gold electrodes

“…The two domains are connected via a protease cleavable linker region [23]. CDH catalyses the oxidation of cellobiose to cellobio-δ-lactone [24], it can also use lactose and glucose as substrates.…”

Rational Combination of Promiscuous Enzymes Yields a Versatile Enzymatic Fuel Cell with Improved Coulombic Efficiency

“…7 While many examples of high power EFCs can be found, [8][9][10][11][12] the vast majority of glucose EFCs report only a single 2e − oxidation, thereby operating at <10 % efficiency. In the recent past, alternative enzymes to the commonly used glucose oxidase (GOx) for glucose oxidation have been explored, namely flavin adenine dinucleotide-dependent glucose dehydrogenase (FAD-GDH), 8,[13][14][15] nicotinamide adenine dinucleotidedependent glucose dehydrogenase (NAD-GDH), [16][17][18] pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH), 19,20 cellobiose dehydrogenase (CDH), 21,22 pyranose oxidase (POx) 23 and pyranose dehydrogenase (PDH).24-27 FAD-GDH and CDH, which both oxidize their substrates at the anomeric (C1) position, are promising alternatives to GOx, because they do not utilize molecular oxygen as their electron acceptor, thus bioanode efficiency is retained in the presence of O 2 (required for the biocathode of most membraneless glucose/oxygen EFCs). 28,29 As an alternative to utilizing an O 2 -insensitive enzyme (such as FAD-GDH), Mano and coworkers were able to almost completely suppress the ability of GOx to reduce O 2 by the replacement of the FAD cofactor with a riboflavin derivative.…”