Resonance Raman characterization of Chromatium vinosum cytochrome c'. Effect of pH and comparison of equilibrium and photolyzed carbon monoxide species

• Published in: Biochemistry (Easton) Vol. 29; no. 17; pp. 4166 - 4174
• Main Authors: Hobbs, J. D, Larsen, R. W, Meyer, T. E, Hazzard, J. H, Cusanovich, M. A, Ondrias, M. R
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01-05-1990
• Subjects: Analytical, structural and metabolic biochemistry; Binding Sites; Biological and medical sciences; Carbon Monoxide - analysis; Chromatium - enzymology; Cytochrome c Group - analysis; Ferric Compounds - analysis; Ferrous Compounds - analysis; Fundamental and applied biological sciences. Psychology; Hemoproteins; Humans; Hydrogen-Ion Concentration; Ligands; Metalloproteins; Photolysis; Protein Conformation; Proteins; Spectrum Analysis, Raman - methods; Hemoprotein; Chromatiaceae; Active site; Molecular dynamics; Chromatium vinosum; Infrared spectrometry; Rhodospirillales; Photolysis; PH; Bacteria; Raman spectrometry; Carbon monoxide; Dimerization; Ultraviolet visible spectrometry
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi00469a020

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.