Resonance Raman spectroscopy of the catalytic intermediates and derivatives of chloroperoxidase from Caldariomyces fumago

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 nu 4 frequencies for the ferric enzyme, and quite low nu 4 frequencies for the ferrous enzyme, low nu 4 frequencies are observed for ferryl compound II and several ferric derivatives. Resonance Raman spectra of chloroperoxidase compound I feature upshifted nu 2, nu 11, and nu 37 frequencies and other characteristics that argue for a (2) A(1u) in preference to a (2)A(2u) ground state for the porphyrin pi-cation radical. A moderately intense anomalously polarized band is observed at a frequency typical for octaethylporphyrin pi-cation radicals, which have been previously assigned as the (2)A(1u) radical type. Similar resonance Raman spectral attributes are observed for horseradish peroxidase compound I, supporting a (2)A(1u) symmetry state assignment for this species also. A (2)A(1u) 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