RESONANCE RAMAN-SPECTROSCOPY OF THE CATALYTIC INTERMEDIATES AND DERIVATIVES OF CHLOROPEROXIDASE FROM CALDARIOMYCES-FUMAGO

Near-ultraviolet resonance Raman spectra of chloroperoxidase derivativ es and high valent intermediates show frequencies that can be systemat ically assigned. In accord with previous observations of low nu(4) fre quencies for the ferric enzyme, and quite low nu(4) frequencies for th e ferrous enzyme, low nu(4) frequencies are observed for ferryl compou nd II and several ferric derivatives. Resonance Raman spectra of chlor operoxidase compound I feature upshifted nu(2), nu(11), and nu(37) fre quencies and other characteristics that argue for a (2)A(1u) in prefer ence to a (2)A(2u) ground state for the porphyrin pi-cation radical. A moderately intense anomalously polarized band is observed at a freque ncy typical for octaethylporphyrin pi-cation radicals, which have been previously assigned as the (2)A(1u) radical type. Similar resonance R aman spectral attributes are observed for horseradish peroxidase compo und I, supporting a (2)A(1u) symmetry state assignment for this specie s 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 enzyme s.