Biochemical and molecular characterization of a manganese peroxidase isoenzyme from Pleurotus ostreatus

In this study we purified and investigated the catalytic properties of a manganese peroxidase isoenzyme produced by the fungus Pleurotus ostreatus in liquid medium with peptone as nitrogen source. The isoenzyme was purified to homogeneity by chromatography on Bio-Rad Q-cartridge, Sephacryl S-200 and Mono-Q with activity yield of 59% and a purification factor of 36. The P. ostreatus MnP obtained had the same pi (3.75) and N-terminal sequence as MnP-1 of Pleurotus eryngii produced in the same medium (both exhibiting Mn-independent activities on phenolic and non-phenolic substrates). However, the N-terminal sequence of this P. ostreatus isoenzyme differed from a previous published sequence of MnP from this fungus. The results obtained show the importance of media composition in the production of different isoenzymes within the same fungal species. We have also demonstrated by Southern blots that the different isoenzymes are probably encoded by different genes, and that the MnP genes in both Pleurotus species are similar but different to those of Phanerochaete chrysosporium.