Studies on Cytochrome c Peroxidase: XV. comparison of manganese porphyrin-containing cytochrome c peroxidase, horseradish peroxidase, and myoglobin

Abstract

Abstract Apoproteins of cytochrome c peroxidase, horseradish peroxidase, and sperm whale myoglobin were recombined with manganese complexes of proto-, hemato-, meso-, and deuteroporphyrins to form manganese porphyrin-protein complexes. These complexes were purified by column chromatography. All the manganese porphyrin-containing cytochrome c peroxidases were crystallized. Light absorption maxima of manganese porphyrins were shifted to longer wave lengths upon binding to these apoproteins. Light absorption maxima of manganese porphyrin-protein complexes and their derivatives were shifted to shorter wave lengths to the extent of 1 to 10 mµ in the order of proto-, hemato-, meso-, and deutero- derivatives. Manganese-porphyrins and their protein complexes exhibited no appreciable electron paramagnetic resonance absorption at -196°. Manganese porphyrin-containing peroxidases reacted with hydroperoxides to form peroxide compounds and catalyzed the peroxidatic oxidation of ferrocytochrome c, ferrocyanide, and ascorbate at reasonable rates. The peroxide compounds of manganese porphyrin-containing horseradish peroxidases were highly stable and appeared to be a manganese (IV) derivative. The peroxide compounds of manganese porphyrin-containing cytochrome c peroxidases were less stable and retained 2 oxidizing equivalents per mole of the enzyme. However, the chemical nature of the compound was not established. Manganese porphyrin-containing myoglobin neither formed peroxide compounds nor exhibited peroxidase activity under comparable conditions. These myoglobin derivatives and their dithionite-reduced compounds did not form complexes with oxygen and carbon monoxide.