Probing the cytochrome c' folding landscape.
The folding kinetics of R. palustris cytochrome c' (cyt c') have been monitored by heme absorption and native Trp72 fluorescence at pH 5. The Trp72 fluorescence burst signal suggests early compaction of the polypeptide ensemble. Analysis of heme transient absorption spectra reveals deviations from two-state behavior, including a prominent slow phase that is accelerated by the prolyl isomerase cyclophilin. A nonnative proline configuration (Pro21) likely interferes with the formation of the helical bundle surrounding the heme.
Beckman Institute, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA.
Ekaterina V
EV
Pletneva
Ziqing
Z
Zhao
Tetsunari
T
Kimura
Krastina V
KV
Petrova
Harry B
HB
Gray
Jay R
JR
Winkler
D021983:Cyclophilins / Q000737:chemistry; D045305:Cytochromes c' / Q000737:chemistry* / Q000235:genetics; D005453:Fluorescence; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D017510:Protein Folding; D017433:Protein Structure, Secondary; D012241:Rhodopseudomonas / Q000235:genetics / Q000378:metabolism; D013816:Thermodynamics
D045305:Cytochromes c'; D021983:Cyclophilins