Conversion of d-glucose to d-erythro-hexos-2,3-diulose (2,3-diketo-d-glucose) by enzyme preparations from the basidiomycete Oudemansiella mucida

Aerobic incubation of crude enzyme extracts from the white rot fungus Oudemansiella mucida with d-glucose resulted in transient accumulation of d-arabino-hexos-2-ulose (1, 2-keto-d-glucose) which was subsequently quantitatively converted into a new tricarbonyl sugar metabolite. d-erythro-hexos-2,3-diulose (2, 2,3-diketo-d-glucose). The latter end-product was derivatized with N,N-diphenylhydrazine; its structure was deduced from formulae of the four major hydrazones isolated from the reaction mixture using thin layer chromatography, and identified by nuclear magnetic resonance and mass spectroscopy, 2 was also obtained on incubations with chemically synthesized 1, and with partially purified preparations of pyranose 2-oxidase. A hypothetical reaction scheme was proposed for two step oxidation of d-glucose to 2 by a single enzyme, pyranose 2-oxidase (EC 1.1.3.10).