NMR INVESTIGATION OF ISOTOPICALLY LABELED CYANIDE DERIVATIVES OF LIGNIN PEROXIDASE AND MANGANESE PEROXIDASE

The H-1 NMR spectroscopy was used to study lignin peroxidase (LiP) and manganese peroxidase (MnP) containing deuterated histidines. LiP and MnP were obtained from a histidine auxotroph of the fungus Phanerochae te chrysosporium grown in the presence of deuterated histidines. The d erivatives with deuterated histidines have allowed a firm assignment o f the protons of the distal and proximal histidines. We have also foun d that the LiP from this strain exhibits different orientations of the 2-vinyl group compared to the LiP from the strain previously studied. Mobility of the group has also been detected, thus explaining the app arent inconsistency between X-ray solid-state and NMR solution data. T he N-15 shift values of N-15-enriched CN- in the cyanide derivatives o f LiP and MnP have also been measured. The shift patterns, both for N- 15 and for the proximal histidine protons of several peroxidases, are consistent with predominant contact shift contributions which reflect the bond strength of the metal-axial ligand. Finally, our results conf irm a correlation between shift values of N-15 and those of proximal h istidine protons and the Fe3+/Fe2+ redox potentials.