Mn-peroxidase from Bjerkandera adusta 90-41. Purification and substrate specificity

Mn-peroxidase has been purified to homogeneity from culture liquid of white-rot fungus Bjerkandera adusta 90-41 grown on medium containing lignosulfonates. According to the data on SDS-PAGE and isoelectrofocusing, the molecular mass of the enzyme is 43 kD and the isoelectric point is 3.5. The pH-optimum in the reaction of MnSO4 oxidation is 4.5. The substrate specificity of the enzyme has been studied. In contrast to previously known Mn-peroxidases from B. adusta, the isolated enzyme has no activity with veratryl alcohol. The enzyme can oxidize ammonium 2, 2-azino-bis(ethyl-6-benzothiazoline sulfonate) (ABTS), o-phenylenediamine, and phenol red in the absence of Mn2+. Oxidation of ABTS and o-phenylenediamine is stimulated by Mn2+, whereas in the reaction of oxidation of phenol red Mn2+ acts as an inhibitor. Some aromatic substrates, such as pyrocatechol and guaiacol, are oxidized only in the presence of Mn2+.