title: Pyranose Dehydrogenase from Agaricus campestris and Agaricus xanthoderma: Characterization and Applications in Carbohydrate Conversions.
abstract: Pyranose dehydrogenase (PDH) is a flavin-dependent sugar oxidoreductase that is limited to a rather small group of litter-degrading basidiomycetes. The enzyme is unable to utilize oxygen as an electron acceptor, using substituted benzoquinones and (organo) metal ions instead. PDH displays a broad substrate specificity and intriguing variations in regioselectivity, depending on substrate, enzyme source and reaction conditions. In contrast to the related enzyme pyranose 2-oxidase (POx), PDHs from several sources are capable of oxidizing α- or β-1→4-linked di- and oligosaccharides, including lactose. PDH from A. xanthoderma is able to perform C-1 and C-2 oxidation, producing, in addition to lactobionic acid, 2-dehydrolactose, an intermediate for the production of lactulose, whereas PDH from A. campestris oxidizes lactose nearly exclusively at the C-1 position. In this work, we present the isolation of PDH-encoding genes from A. campestris (Ac) and A. xanthoderma (Ax) and a comparison of other so far isolated PDH-sequences. Secretory overexpression of both enzymes in Pichia pastoris was successful when using their native signal sequences with yields of 371 U·L-1 for AxPDH and 35 U·L-1 for AcPDH. The pure enzymes were characterized biochemically and tested for applications in carbohydrate conversion reactions of industrial relevance.
authors: Food Biotechnology Laboratory, BOKU-University of Natural Resources and Life Sciences Vienna, Muthgasse 11, Vienna 1190, Austria. petra.wuehrer@boku.ac.at.
authors: Petra
authors: P
authors: Staudigl
authors: Food Biotechnology Laboratory, BOKU-University of Natural Resources and Life Sciences Vienna, Muthgasse 11, Vienna 1190, Austria. iris.krondorfer@boku.ac.at.
authors: Iris
authors: I
authors: Krondorfer
authors: Food Biotechnology Laboratory, BOKU-University of Natural Resources and Life Sciences Vienna, Muthgasse 11, Vienna 1190, Austria. dietmar.haltrich@boku.ac.at.
authors: Dietmar
authors: D
authors: Haltrich
authors: Food Biotechnology Laboratory, BOKU-University of Natural Resources and Life Sciences Vienna, Muthgasse 11, Vienna 1190, Austria. clemens.peterbauer@boku.ac.at.
authors: Clemens K
authors: CK
authors: Peterbauer