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

Area of Science:

• Biochemistry
• Enzymology
• Mycology

Background:

• White-rot fungi are key lignin degraders.
• Manganese peroxidases (MnPs) are crucial enzymes in ligninolysis.
• Bjerkandera adusta is a known producer of lignin-degrading enzymes.

Purpose of the Study:

• To purify and characterize manganese peroxidase (MnP) from Bjerkandera adusta 90-41.
• To investigate the substrate specificity and kinetic properties of the isolated MnP.
• To compare the novel MnP with previously identified MnPs from the same species.

Main Methods:

• Purification of MnP from fungal culture liquid using standard protein purification techniques.
• Enzyme characterization via SDS-PAGE and isoelectric focusing to determine molecular mass and isoelectric point.
• Enzyme activity assays to determine pH optimum and substrate specificity, including the role of Mn2+.

Main Results:

• MnP was purified to homogeneity from Bjerkandera adusta 90-41.
• The enzyme has a molecular mass of 43 kD and an isoelectric point of 3.5.
• Optimal pH for MnSO4 oxidation is 4.5; the enzyme oxidizes ABTS, o-phenylenediamine, and phenol red without Mn2+.
• Mn2+ stimulates ABTS and o-phenylenediamine oxidation but inhibits phenol red oxidation.
• Pyrocatechol and guaiacol oxidation requires the presence of Mn2+.
• Unlike other B. adusta MnPs, this enzyme lacks veratryl alcohol activity.

Conclusions:

• A novel manganese peroxidase from Bjerkandera adusta 90-41 has been isolated and characterized.
• The enzyme exhibits unique substrate specificity and regulatory properties concerning Mn2+.
• These findings contribute to understanding the diversity and function of MnPs in lignin degradation.