ABSTRACT
Near-ultraviolet resonance Raman spectra of chloroperoxidase derivatives and high valent intermediates show frequencies that can be systematically assigned. In accord with previous observations of low v4 frequencies for the ferric enzyme, and quite low v4 frequencies for the ferrous enzyme, low v4 frequencies are observed for ferryl compound II and several ferric derivatives. Resonance Raman spectra of chloroperoxidase compound I feature upshifted v2, v11, and v37 frequencies and other characteristics that argue for a 2A1u in preference to a 2A2u ground state for the porphyrin phi-cation radical. A moderately intense anomalously polarized band is observed at a frequency typical for octaethylporphyrin phi-cation radicals, which have been previously assigned as the 2A1u radical type. Similar resonance Raman spectral attributes are observed for horseradish peroxidase compound I, supporting a 2A1u symmetry state assignment for this species also. A 2A1u symmetry state assignment for chloroperoxidase and horseradish peroxidase compounds I is consistent with the beta-pyrrole substituent pattern of the protoporphyrin hemes found in these enzymes.
