Functional aspects of cellobiose dehydrogenase Applications for biosensor development

Abstract: Electrochemcial investigations were conducted for elucidating and understanding the relation between the various electron transfer processes occurring in cellobiose dehydrogenase (CDH) bound to an electrode surface. Substrate inhibition caused by cellobiose was proven to act in competition with the electron transfer to a two-electron acceptor and under a partial inhibition mechanism for the internal electron transfer process. The implications of these findings have been discussed in relation to what has been stated previously but also exploited for analytical purposes by adjusting the sensitivity of the CDH based biosensor for catecholamines. Different thiols were used to form self-assembled monolayers (SAM) on gold electrodes and these have been used to electrochemically investigate and characterise the direct electron transfer reaction of CDH from two white-rot fungi (Phanerochaete sordida and Trametes villosa), and one soft-rot fungus (Myriococcum thermophilum) in the absence and presence of cellobiose. The high efficiency of the direct electron transfer between Phanerochaete sordida CDH and Trametes villosa CDH and SAM modified Au electrodes was emphasised, and a potential application of these enzymes was demonstrated by development of a third-generation biosensor for lactose determination. Toxic waste-water quinone type pollutants were also determined using a Phanerochaete chrysosporium CDH based biosensor, working under a mediated electron transfer mechanism.