Oxalate oxidase from Ceriporiopsis subvermispora: Biochemical and cytochemical studies

The enzyme oxalate oxidase was identified in mycelial extracts of the basid iomycete Ceriporiopsis subvermispora and thereafter purified to homogeneity . The purification procedure included only three steps: Q-Sepharose chromat ography, precipitation at pH 3.0, and phosphocellulose chromatography. The enzyme is a 400-kDa homohexamer, as determined by gel permeation in Sephade x G-200 and SDS-polyacrylamide gel electrophoresis. Isoelectrofocusing reve aled a pi of 4.2. Optimal activity was obtained at pH 3.5 and at 45 degrees C. The purified enzyme has K-m and k(cat) values of 0.1 mM and 88 s(-1), r espectively. It is highly specific for oxalate, although it is inhibited at concentrations of this substrate above 2.5 mM. Hystochemistry studies cond ucted over mycelium slices showed reactions products in both endocellular a nd periplasmic associated elements. A possible connection between the intra cellular metabolism of oxalate and the extracellular ligninolytic activity of the fungus is proposed. (C) 1999 Academic Press.