Evidence for a new extracellular peroxidase Manganese-inhibited peroxidase from the white-rot fungus Bjerkandera sp. BOS 55

A novel enzyme activity was detected in the extracellular fluid of Bjerkandera sp, BOS 55. The purified enzyme could oxidize several compounds, such as Phenol red, 2,6-dimethoxyphenol (DMP), Poly R-478, ABTS and guaiacol, with H₂O₂ as an electron acceptor. In contrast, veratryl alcohol was not a substrate. This enzyme also had the capacity to oxidize DMP in the absence of H₂O₂. With some substrates, a strong inhibition of the peroxidative activity by Mn²⁺ was observed. Phenol red oxidation was inhibited by 84% with only 1 mM of this metal ion. Because DMP oxidation by this enzyme is only slightly inhibited by Mn²⁺, this substrate should not be used in assays to detect manganese peroxidase. The enzyme is tentatively named 'Manganese-Inhibited Peroxidase'.