Proton NMR Characterization of the Ferryl Group in Model Heme Complexes and Hemoproteins: Evidence for the FeIV=O Group in Ferryl Myoglobin and Compound II of Horseradish Peroxidase

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The proton NMR spectra of model porphyrin complexes possessing the ferryl, FeIV=O, group are reported and assigned. The only resonance shifted well outside the diamagnetic region is that of the meso protons. Moreover, these model compounds exhibit hyperfine shift patterns (particularly for the substituents found in natural porphyrins) that are different from those found for other characterized iron-porphyrin complexes. Deuterium labeling of the meso position of hemin reconstituted into sperm whale myoglobin and horseradish peroxidase reveals that both the hydrogen peroxide treated myoblobin (ferryl myoglobin) and horseradish peroxidase compound II exhibit only meso H resonances with significant hyperfine shift and that these shifts are essentially the same as those found in the low-spin FeIV=0 model complexes. Hence, the 1H NMR data can be taken as evidence for the presence of the ferryl group at the active site of both ferryl myoglobin and compound II of horseradish peroxidase. © 1983, American Chemical Society. All rights reserved.

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Journal of the American Chemical Society

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