C-3 oxidation of non-reducing sugars by a fungal pyranose dehydrogenase: spectral characterization

The quinone-dependent pyranose dehydrogenase (PDH) purified from mycelial extracts of the basidiomycete fungus Agaricus meleagris catalyzed oxidation of the non-reducing oligosaccharides sucrose, melezitose and erlose at C-3 of their terminal glucopyranosyl moiety while α,α-trehalose was double oxidized at both C-3 and C-3′. Analogously, using MS and in situ NMR spectroscopy, formation of C-3 carbonyl derivatives was also demonstrated with methyl-α-d-Glcp, methyl-β-d-Glcp and methyl-α-d-Galp. Yields of conversions performed at room temperature with 10 mM sugars and 1,4-benzoquinone as an electron acceptor in non-buffered systems were ≥90% within 3–20 h, depending on substrate.