On the Mechanism of the Laccase-Mediator System in the Oxidation of Lignin

In an effort to elucidate the role of phenolic and non-phenolic lignin subunits in a laccase mediator (LM) system, vanillyl alcohol was oxidized with laccase in the presence and absence of the mediator 1-hydroxybenzotriazol (HBT). Furthermore, the role of phe- nolic, aliphatic hydroxyl, and carboxylic Introduction acid moieties in lignin degradation was elucidated by selectively blocking them. The modified samples were then sub- jected to laccase and laccase ± HBT treatments. On the basis of this data it was possible to establish the role of this mediator. HBT mediates the oxidation of lignin by inducing side-chain oxida- tion and oxygen-addition products rath- er than oxidative coupling reactions.