PROTON NMR INVESTIGATION INTO THE BASIS FOR THE RELATIVELY HIGH REDOX POTENTIAL OF LIGNIN PEROXIDASE

Lignin peroxidase shares several structural features with the well-studied horseradish peroxidase and cytochrome c peroxidase but carries a higher redox potential. Here the heme domain of lignin peroxidase and the lignin peroxidase cyanide adduct was examined by H-1 NMR spectroscopy, including nuclear Overhauser effect and two-dimensional measurements, and the findings were compared with those for horseradish peroxidase and cytochrome c peroxidase. Structural information was obtained on the orientation of the heme vinyl and propionate groups and the proximal and distal histidines. The shifts of the epsilon-1 proton of the proximal histidine were found to be empirically related to the Fe3+/Fe2+ redox potentials.