Degradation and Solubilization of 13C_, 14C-side Chain Labeled Synthetic Lignin (Dehydrogenative Polymerizate) by Laccase III of Coriolus versicolor

During the decay of wood by the typical white rot fungus Coriolus versicolor, Laccase III was the most abundantly secreted phenol oxidase. In this study, we proposed a possibility of the intermediate degradation steps of polymeric lignin by a purified Laccase III using synthetic [β- 13 C] and [β- 14 C]lignin (DHP). When the [β- 14 C]DHP was incubated with Laccase III, the water-soluble degradation product formed was about 8% of the applied [β- 14 C]DHP. The enzymic attack of Laccase III catalyzed the cleavage of the intermonomer linkages in the side chain structure of the polymeric lignin. In polymeric lignin metabolism by this fungus, laccase activity was closely related to the accumulation of water-soluble degradation products.