title: Resonance Raman characterization of Chromatium vinosum cytochrome c'. Effect of pH and comparison of equilibrium and photolyzed carbon monoxide species.
abstract: Resonance Raman spectra of Chromatium vinosum cytochrome c' have been obtained for the five pH-dependent states of the protein [i.e., types I (pH 7), II (pH 10), and III (pH 12) of the ferric protein and type a (pH 7) and type n (pH 12) of the ferrous protein]. The raman spectra of type II and type a are consistent with those of high-spin, 5-coordinate heme proteins, such as deoxyhemoglobin, while spectra of type III and type n correspond more closely to those of low-spin, ferric and ferrous cytochrome c, respectively. Spectra of the CO-bound equilibrium species qualitatively resemble those of carbon monoxy human HbA. However, both the Fe-C and C = O stretching modes of the ligated species exhibit pH-dependent frequency shifts. Our data also indicate that CO photolysis is much more efficient at pH 7 than at pH 12. Moreover, the spectra of the photolytic transients suggest that unique, high-spin species are formed subsequent to CO photolysis from both type a and type n species.
authors.affiliation: Department of Chemistry, University of New Mexico, Albuquerque 87131.
authors.forename: J D
authors.initials: JD
authors.lastname: Hobbs
authors.forename: R W
authors.initials: RW
authors.lastname: Larsen
authors.forename: T E
authors.initials: TE
authors.lastname: Meyer
authors.forename: J H
authors.initials: JH
authors.lastname: Hazzard
authors.forename: M A
authors.initials: MA
authors.lastname: Cusanovich
authors.forename: M R
authors.initials: MR
authors.lastname: Ondrias
mesh_terms: D001665:Binding Sites; D002248:Carbon Monoxide / Q000032:analysis*; D002844:Chromatium / Q000201:enzymology*; D003574:Cytochrome c Group / Q000032:analysis*; D005290:Ferric Compounds / Q000032:analysis; D005296:Ferrous Compounds / Q000032:analysis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008024:Ligands; D010782:Photolysis; D011487:Protein Conformation; D013059:Spectrum Analysis, Raman / Q000379:methods
chemical_list: D003574:Cytochrome c Group; D005290:Ferric Compounds; D005296:Ferrous Compounds; D008024:Ligands; D002248:Carbon Monoxide