Analysis of D-glucose metabolism of wood decay fungi using 13C-NMR and 13C-labeled substrates
T H de Koker, M D Mozuch, P J Kersten
D-Glucose metabolism is thought to be important during wood decay by fungi, not only for anabolic and catabolic purposes of central metabolism, but also as a potential source of peroxide required by extracellular peroxidases. There has been some confusion in the literature as to whether this peroxide-generating activity is of the glucose 1-oxidase or pyranose 2-oxidase (glucose 2-oxidase) type with various fungi or even within the same fungal species. Definitive classification requires accurate identification of the enzymatic products D-glucono-1,5-lactone and D-arabino-2-hexosulose (glucosone) with glucose 1-oxidase and pyranose 2-oxidase, respectively. We used 13C-NMR to distinguish these reactions starting with 13C-labeled glucose. The use of labeled substrates simplifies analysis and greatly increases detection sensitivity without requiring the isolation or derivatization of metabolites. We synthesized 13C-1-glucosone to study subsequent metabolism with crude enzyme preparations. Preliminary results with Phanerochaete chrysosporium are presented.