Nature of the cytochrome c molten globule.
We have employed fluorescence energy transfer (FET) kinetics to probe unfolded and molten globule states of five dansyl (Dns) variants of Saccharomyces cerevisiae iso-1 cytochrome c. The covalently bound Fe(III) heme group quenches Dns fluorescence by energy transfer; measurements of FET kinetics yielded distributions of D-A distances (P(r)) for these states. The P(r) distributions and corresponding mean force potentials (U(r)) show that the cytochrome c molten globule is a highly structured state with a substantial number of native interactions. Wide P(r) distributions directly reflect the dynamic nature and conformational diversity of this molten globule. P(r) distributions for the "burst-phase" refolding intermediate suggest that the equilibrium cytochrome c molten globule is not a suitable model for early intermediates formed during protein refolding.
Pletneva
Ekaterina V
EV
Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA.
Gray
Harry B
HB
Winkler
Jay R
JR
D045304:Cytochromes c / Q000737:chemistry*; D005453:Fluorescence; D007700:Kinetics; D044367:Phase Transition; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding
D045304:Cytochromes c