In vitro depolymerization of lignin by manganese peroxidase of Phanerochaete chrysosporium

Homogeneous manganese peroxidase catalyzed the in vitro partial depolymerization of four different ¹⁴C-labeled synthetic lignin preparations. Gel permeation profiles demonstrated significant depolymerization of ¹⁴C-sidechain-labeled syringyl lignin, a ¹⁴C-sidechain-labeled syringyl-guaiacyl copolymer (angiosperm lignin), and depolymerization of ¹⁴C-sidechain- and ¹⁴C-ring-labeled guaiacyl lignins (gymnosperm lignin). 3,5-Dimethoxy-1,4-benzoquinone, 3,5-dimethoxy-1,4-hydroquinone, and syringylaldehyde were identified as degradation products of the syringyl and syringyl-guaiacyl lignins. These results suggest that manganese peroxidase plays a significant role in the depolymerization of lignin by Phanerochaete chrysosporium.