Hydroperoxidase activities of ferrihemes: heme analogs of peroxidase enzyme intermidiates

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Abstract
By reaction of deuteroferriheme (DFH) with peroxo acids, spectroscopically distinct and peroxidatically active deuteroferriheme-peroxide compounds (DPC) were formed. These species closely resembled, and were probably identical with, the species formed by reaction of DFH with H2O2, which was previously considered to be an analogue of peroxidase compound I. Stopped-flow spectrophotometric titration studies implied that DPC was formed by reaction of 1.0 .+-. 0.2 mol of DFH with 1 mol of peroxo acid and the spectral change accompanying formation of DPC was independent of the peroxo acid oxidant used. Titration of the oxidizing power of DPC formed with H2O2 implied that submaximal yields of DPC were obtained, a result that could implicate DPC species as analogues of catalase compound I in the catalase action of ferrihemes. Preliminary results suggested that DPC may involve both monomeric and dimeric heme components.