Oxidation of 1,2,4,5-Tetramethoxybenzene by Lignin Peroxidase ofPhanerochaete chrysosporium

We have reinvestigated the lignin peroxidase-catalyzed oxidation of 1,2,4,5-tetramethoxybenzene (TMB) by using presteady-state and steady-state kinetic methods. Our presteady-state kinetic results show that the reaction of compound I with TMB obeyed second order kinetics with a rate constant of 1.1 × 107M−1s−1. The reaction of compound II with TMB exhibits a hyperbolic concentration dependence with aKdof 16 μMandk= 24 s−1. The stoichiometry of TMB oxidation during steady state is two TMB cation radicals formed per H2O2consumed. These results clearly show that TMB is a good substrate for both compounds I and II of lignin peroxidase.