MPS seminar Roland Ludwig

MPS-seminar

  Strange Carbohydrate Dehydrogenases/Oxidases from Fungi: How to Use them in Bioconversion and Analytic Applications?     Roland Ludwig, BOKU University of Natural Resources & Applied Life Science, Department of Food Science & Technology, A-1190 Vienna, Austria   Tuesday the 24 of June,  Lecturehall B at 14.00     Abstract: In the past years, carbohydrate oxidizing enzymes from wood-degrading fungi containing FAD and heme b cofactors were discovered and used to oxidize a broad spectrum of mono-, di- and oligosaccharides specifically at the positions C1, C2 or C3. They enable an elegant approach without the need for protective groups to produce various aldonic acids, 2- and 3-keto-sugars, which can be used for further syntheses. Additionally, their catalytic and molecular properties aroused interest for the application as biological recognition elements in biosensors. The biocatalytic use of these enzymes, namely, cellobiose dehydrogenase, pyranose 2-oxidase and pyranose dehydrogenase is, however, limited by their low activity with oxygen or their dependence on suitable electron acceptors. The problem was tackled by using laccase, which is capable to re-oxidize most of these electron acceptors, as regenerating enzyme. This minimises the amount of the employed electron acceptors to catalytic amounts, accelerates the reaction rate and increases biocatalyst stability by suppressing the formation of reactive oxygen species. The application of laccase as regenerating enzyme for FAD and NAD(P)+ dependent dehydrogenases is demonstrated by several examples of homogeneous or heterogenzied enzymatic reaction systems. The analytic application of these enzymes in amperometric biosensors depend on catalytic specificity, as well as on efficient electron transfer from the catalytic center to the electrode. The screening and selection of suitable enzymes, meeting both requirements and the application in carbohydrate detecting biosensors will be also covered.   Host: Lo Gorton Lo.Gorton@analykem.lu.se

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