Influence of the proximal ligand in the dismutation of hydrogen peroxide catalysed by manganese– and iron–porphyrin complexes

Abstract

Using manganese– or iron–porphyrin complexes with a non-labile proximal ligand containing an oxygen or a nitrogen atom, the influence of the proximal ligand in hydrogen peroxide dismutation has been quantified; catalase activity is lower with a proximal oxygen(the axial ligand of the prosthetic ferriprotoporphyrin of catalase) than with a nitrogen ligand and the main role of the proximal oxygen ligand is to inhibit the oxygenase activity.