title: The stability of the cytochrome c scaffold as revealed by NMR spectroscopy.
abstract: NMR spectroscopy was used to study the effect of guanidinium chloride on the unfolding of horse heart and yeast iso-1 cytochrome c under mild alkaline conditions. The structural changes on the horse heart protein were detected through NOESY (Nuclear Overhauser Effect SpectroscopY) experiments whereas (15)N-(1)H heteronuclear NMR was used to monitor the behavior of the yeast protein. The latter represents the first characterization through (15)N-(1)H heteronuclear NMR spectroscopy of the guanidinium chloride induced unfolding of mitochondrial cytochrome c. The presence of denaturants decreases the temperature at which the native Met80 axial ligand is displaced from the iron center under the present mild alkaline conditions. The process can be described in terms of protein fragments behaving as unfolding units of different stability. The comparison between the two proteins indicates that the loop+helix connecting the proximal and distal sites, as well as the long Met80-containing loop immediately after a short helix, are structural characteristics of mitochondrial cytochrome c that appear to be responsible for the Met80-iron(III) bond fragility.
authors.affiliation: School of Biomedical and Chemical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA 6009, Australia.
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Berners-Price
authors.forename: Ivano
authors.initials: I
authors.lastname: Bertini
authors.forename: Harry B
authors.initials: HB
authors.lastname: Gray
authors.forename: Georgios A
authors.initials: GA
authors.lastname: Spyroulias
authors.forename: Paola
authors.initials: P
authors.lastname: Turano
mesh_terms: D000818:Animals; D045304:Cytochromes c / Q000737:chemistry*; D006736:Horses; D008958:Models, Molecular; D009206:Myocardium / Q000737:chemistry; D019906:Nuclear Magnetic Resonance, Biomolecular; D011487:Protein Conformation; D011489:Protein Denaturation; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D045304:Cytochromes c