Oxygen exchange between high-valent metal–oxo complexes and bulk water has been monitored for nonligated model porphyrins (hemin, FeTDCPPS, MnTMPyP) and the axially ligated microperoxidase-8 (MP-8). Exchange extents up to 90 ere measured for MP-8 in spite of the presence of an axial histidine ligand and accompanied by the formation of nonlabelled H2O2 from H218O2. These results point to the existence of a mechanism for oxygen exchange between the high-valent iron–oxo complex and the solvent different from the so-called "oxo-hydroxo tautomerism." Regeneration of the primary oxidant, H2O2, and oxygen exchange by axially ligated porphyrins can be explained by a mechanism involving the reversibility of compound I formation.
|Journal||Biochemical and Biophysical Research Communications|
|Publication status||Published - 2000|