title: Excited state lifetimes in cytochromes measured from Raman scattering data: evidence for iron-porphyrin interactions.
abstract: Resonance Raman scattering excitation profile data have been obtained on ferrocytochromes c and b5 in the alpha absorption band region. We observe in cytochrome c that the shape of the excitation profile agrees with the absorption band shape, while in cytochrome b5 it does not. In addition, we observe in cytochrome b5 a linewidth substantially larger than that in cytochrome c. From our data we conclude that the excited state lifetime in cytochrome c is longer than that in cytochrome b5 and that in cytochrome b5 the relaxation of the pi-pi* excited state configuration of the porphyrin ring is different in the x direction than in the y direction. Possible origins of these effects due to coupling to the d-d transitions of the iron atom are discussed.
mesh_terms: D003574:Cytochrome c Group; D003580:Cytochromes; D005296:Ferrous Compounds; D008968:Molecular Conformation; D011166:Porphyrins; D013053:Spectrophotometry; D013059:Spectrum Analysis, Raman; D013696:Temperature
chemical_list: D003574:Cytochrome c Group; D003580:Cytochromes; D005296:Ferrous Compounds; D011166:Porphyrins