Abstract

3rd Generation Biosensors for Sugar Analysis

Lo Gorton, Professor, Lund University

A number of new sugar oxidising redox enzymes, viz. pyranose dehydrogenase (PDH), pyranose oxidase (P2O), and cellobiose dehydrogenase (CDH) have recently been electrochemically characterised for use in biosensors and biofuel cell anodes. These fungal redox enzymes contain strongly bound FAD in the active site. CDH additionally also contains a cytochrome b. Electron transfer between these enzymes and electrodes can be obtained through different mediated approaches. Additionally due to its cytochrome b domain CDH shows very facile direct electron transfer characteristics with electrodes making 3rd generation bioelectrodes possible. CDH similarly to glucose oxidase oxidises the sugar on the C1 carbon making it anomeric specific and selective for the ß-form. Depending on the origin class I CDHs selectively oxidise lactose and cellodextrins, whereas class II CDH may also oxidise glucose [4,5]. In contrast PDH and P2O oxidise the sugar on the C2 or C3 carbon (or on both) making them anomeric insensitive. Both PDH and P2O are highly unselective and PDH even oxidises sucrose with a high turn over rate. Additionally especially for PDH there is a possibility that the oxidation product is also a substrate and one sugar molecule can be oxidised at least twice and is thus a very valuable redox enzyme for biofuel cell studies.