THE EFFECT OF IRON DISPLACEMENT OUT OF THE PORPHYRIN PLANE ON THE RESONANCE RAMAN-SPECTRA OF HEME-PROTEINS AND IRON PORPHYRINS

The causes ot the strong coupling ot the iron-histidine vibration to t he Soret resonance in the resonance Raman spectra ot deoxyhemoglobin, myoglobin, and peroxidase are explored, using the vibronic theory. It is shown that the extent ot the iron displacement out ot the plane ot the porphyrin nitrogens is the main structural parameter controlling t he Fe-N(His) band features, such as the dependence ot its frequency an d intensity on the protein conformation and number ot the axial ligand s, time evolution after the photolysis ot the diatomic complexes ot th e proteins under consideration, and inverse relationship between the c hanges Fe-N(His) and nu4 porphyrin breathing mode frequencies.