title: Mn-dependent peroxidase from the lignin-degrading white rot fungus Phlebia radiata.
abstract: A homogeneous Mn-dependent peroxidase (MnP) was purified from the extracellular culture fluid of the lignin-degrading white rot fungus Phlebia radiata by anion exchange chromatography. The enzyme had a molecular weight of 49,000 and pI 3.8. It was a glycoprotein, containing carbohydrate moieties accounting for 10% of the molecular weight. Mn-peroxidase was capable of oxidizing phenolic compounds in the presence of H2O2, whereas the effect on nonphenolic lignin model compounds was insignificant. MnP contained protoporphyrin IX as a prosthetic group. During enzymatic reactions H2O2 converted the native MnP to compound II. Mn2+ was essential in completing the catalytic cycle by returning the enzyme to its native state. The oxidation of ultimate substrates was dependent on superoxide radicals, O2- and probably on Mn3+ generated during the catalytic cycle. MnP exhibited high activity of NADH oxidation without exogenously added H2O2. It was shown to produce H2O2 at the expense of NADH.
authors.affiliation: VTT, Biotechnical Laboratory, Espoo, Finland.
authors.forename: E
authors.initials: E
authors.lastname: Karhunen
authors.forename: A
authors.initials: A
authors.lastname: Kantelinen
authors.forename: M L
authors.initials: ML
authors.lastname: Niku-Paavola
mesh_terms: D005658:Fungi / Q000032:analysis*; D007525:Isoelectric Focusing; D008031:Lignin / Q000378:metabolism*; D009243:NAD; D010084:Oxidation-Reduction; D010544:Peroxidases / Q000302:isolation & purification*; D011489:Protein Denaturation; D013053:Spectrophotometry
chemical_list: D009243:NAD; D008031:Lignin; D010544:Peroxidases; C051129:manganese peroxidase