Structural features of the cytochrome C molten globule revealed by fluorescence energy transfer kinetics.
Nonnative states of proteins are involved in a variety of cellular processes, including translocation of proteins across membranes and formation of amyloid fibrils. Probes that report on the structural heterogeneity of a polypeptide ensemble could resolve ambiguities in the classification of these states. Employing fluorescence energy transfer kinetics, we have shown that added anions shift the equilibrium between the compact and extended polypeptide structures that are present during refolding of Saccaromyces cerevisiae iso-1 cytochrome c. Specifically, at high salt concentrations (>/=700 mM), all of the polypeptides are compact with a mean C-terminal fluorophore-heme separation quite close to that in the native protein (25 A).
Lyubovitsky
Julia G
JG
Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA.
Gray
Harry B
HB
Winkler
Jay R
JR
D002942:Circular Dichroism; D003574:Cytochrome c Group / Q000737:chemistry*; D045304:Cytochromes c; D004735:Energy Transfer; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry; D005656:Fungal Proteins / Q000737:chemistry; D007700:Kinetics; D011487:Protein Conformation; D017510:Protein Folding; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry*
C014059:CYC1 protein, S cerevisiae; D003574:Cytochrome c Group; D005456:Fluorescent Dyes; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; D045304:Cytochromes c