Cytochrome c peroxidase Compound ES is identical to horse radish peroxidase compound I in iron ligand distances.

X-ray absorption studies of Compound ES of cytochrome c peroxidase show a short ion-oxygen distance of 1.68+/-0.04angstroms, an ion-histidine distance of 1.93+/-0.03angstroms, and an iron- pyrrole nitrogen average of 2.04+/-0.02angstroms. This is identical within the error with the reported structure of horse radish peroxidase Compound I (Chance et al., 1984, Arch. Boichem. Biophy., 235, pp. 596-611). Comparisons of the structures of myoglobin peroxide (M. Chance et al., 1984, Biochemistry, submitted), Compound ES, and the intermediates of horse radish peroxidase reveal the possible mechanisms for the stabilization of free radical species generated during catalysis.