Single-electron transfer processes and the reaction mechanism of enzymic degradation of lignin

Abstract

The lignin-degrading, ‘H 2O 2-dependent oxygenase’ from Phanerochaete chrysosporium oxidised veratryl alcohol without incorporating oxygen into the substrate. It also catalysed α-β cleavage of a non-phenolic diarylpropane substrate in the absence of oxygen. Studies with tris(phenanthroline)iron(III) established the importance of single-electron transfer in bringing about α-β cleavage. We propose that the lignin-degrading enzyme functions not as an oxygenase but as a peroxidase and that the oxidation reactions are brought about by initial single-electron transfer between the aromatic ring and a high redox oxy-ferryl active site in the enzyme. Lignin degradation Single-electron transfer Cα-Cβ bond cleavage Phanerochaete chrysosporium Peroxidase compound I