A FUNGAL METABOLITE MEDIATES DEGRADATION OF NONPHENOLIC LIGNIN STRUCTURES AND SYNTHETIC LIGNIN BY LACCASE

Lignin peroxidase is generally considered to be a primary catalyst for oxidative depolymerization of lignin by white-rot fungi. However, som e white-rot fungi lack lignin peroxidase. Instead, many produce laccas e, even though the redox potentials of known laccases are too low to d irectly oxidize the non-phenolic components of lignin, Pycnoporus cinn abarinus is one example of a laccase-producing fungus that degrades li gnin very efficiently. To overcome the redox potential barrier, P. cin nabarinus produces a metabolite, 3-hydroxyanthranilate that can mediat e the oxidation of non-phenolic substrates by laccase, This is the fir st description of how laccase might function in a biological system fo r the complete depolymerization of lignin.