The reaction between metmyoglobin and alkyl hydroperoxides

Abstract

The intermediate compounds which result from the reaction of alkyl hydro-peroxides with metmyoglobin are spectroscopically the same, and identical with that produced by hydrogen peroxide. The compound is formed irreversibly according to the equation [image] where X is a transient oxidizing entity. At pH''s less than 8.0 a side reaction is produced similar to that in the hydrogen peroxide system. Above pH 9.0 no side reaction, which destroys the hemoprotein, is observed; however a large excess of hydroperoxide is required for complete formation of the intermediate. Addition of a reducing agent to metmyoglobin before hydroperoxide reduces the side reaction. The same effect is brought about by using a large excess of peroxide. Reduction with ferrocyanide shows the intermediate to have one oxidizing equivalent relative to metmyoglobin, and the intermediate may thus be considered as a compound in which Fe has an effective oxidation number of +4. A mechanism is proposed for the overall reaction of hydrogen peroxide and hydroperoxide with metmyoglobin involving competition reactions of the transient oxidizing entity, which is produced during the formation of the intermediate compound.