Regulatory Mechanism for Oxalate Production by the Enzymes and Its Related System in Wood-rotting Fungi.

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A role of oxalate producing enzyme systems in wood rotting fungi has not been elucidated. Most of brown rot fungi which attack wooden parts of houses have a strong activity to produce oxalic acid and they are tolerant to copper wood preservaties, including CCA (Copper, chrome and arsenate), because they detoxicate the copper with oxalate produced to form insoluble copper oxalate.As a result, following findings have been obtained.1.Oxalate which was known to inhibit the one elctron oxidation by lignin peroxidase was found also to inhibit the cleavage nonphenolic beta-O-4LCC model compound between lignin model moiety and glucose.2.Three enzymes, including oxalate producing enzyme (glyoxylate oxidase), oxalate decarboxylase, and formate dehydrogenase were isolated from a white-rot fungus Coriolus versicolor. Formate dehydrogenase was first cell-free extracted from wood rotting fungi by this investigation.3.We succeeded in isolating and purifying a new type of cytochrome c dependent glyoxylate dehydrogenase from copper tolerant brown rot fungus Tyromyces palustris. Spectral analysis of the enzyme showed that it belongs to a family of flavohemoproteins. FMN was found to be a prosthetic group. Thus, oxalate production was found to be catalyzed by the electron transport system with cytochrome c and may be controlled by inhibition of the electron transportation system.