1mqv

Publication Abstract from PubMed

We employed fluorescence energy-transfer probes to investigate the polypeptide dynamics accompanying cytochrome c' folding. Analysis of fluorescence energy-transfer kinetics from wild-type Trp-72 or Trp-32 in a crystallographically characterized (1.78 A) Q1A/F32W/W72F mutant shows that there is structural heterogeneity in denatured cytochrome c'. Even at guanidine hydrochloride concentrations well beyond the unfolding transition, a substantial fraction of the polypeptides ( approximately 50%) adopts compact conformations (tryptophan-to-heme distance, approximately 25 A) in both pseudo-wild-type (Q1A) and mutant proteins. A burst phase (< or =5 ms) is revealed when stopped flow-triggered refolding is probed by tryptophan intensity: measurements on the Q1A protein show that approximately 75% of the Trp-72 fluorescence (83% for Trp-32) is quenched within the mixing deadtime, suggesting that most of the polypeptides have collapsed.

Structural features of cytochrome c' folding intermediates revealed by fluorescence energy-transfer kinetics.,Lee JC, Engman KC, Tezcan FA, Gray HB, Winkler JR Proc Natl Acad Sci U S A. 2002 Nov 12;99(23):14778-82. Epub 2002 Oct 29. PMID:12407175^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.