The enzyme pyranose oxidase (pyranose:oxygen-2-oxidoreductase, EC 1.1.3.10) catalyses the oxidation of D-glucose and other aldopyranoses, at carbon 2, in the presence of molecular oxygen producing hydrogen peroxide and the corresponding carbonyl sugars. This enzyme is present in several white-rot fungi in which it is believed to play an important part in lignin degradation, supplying hydrogen peroxide to the lignin peroxidases and also reducing toxic quinones that are formed during the process.

Not only the participation of pyranose oxidase in these fungi metabolism is unclear as not many information is available about its biochemical and biophysical properties. Typically the enzyme is a relatively large flavin adenine dinucleotide intracelular glycoprotein. The enzyme itself has been relatively poorly investigated and there seem to be some inconsistencies with respect to a number of structural properties among pyranose oxidases from different fungal sources.

We have purified pyranose oxidase to homogeneity from the basidiomycete fungus Coriolus versicolor using precipitation with ammonium sulphate, hydrophobic interaction and ion-exchange chromatographic techniques. Nevertheless, we were only able to achieve a partial purification of the pyranose oxidase extracted from Bjerkandera sp. due to stability problems. The enzyme from Bjerkandera also presents a much higher molecular weight than the enzyme of Coriolus. These facts along with the limited knowledge of this species metabolism justify the interest in continuing our studies.