Refolding kinetics of cytochrome c(551) reveals a mechanistic difference between urea and guanidine.


Abstract

The energetic parameters for the folding of small globular proteins can be very different if derived from guanidine hydrochloride (GdnHCl) or urea denaturation experiments. A study of the equilibrium and kinetics of the refolding of wild-type (wt) cytochrome c(551) (cyt c(551)) from Pseudomonas aeruginosa and of two site-directed mutants (E70Q and E70V) shows that the nonionic nature of urea reveals the role of a salt bridge between residues E70 and K10 on the transition state, which is otherwise completely masked in GdnHCl experiments. Mixed denaturant refolding experiments allow us to conclude that the masking effect of GdnHCl is complete at fairly low GdnHCl concentrations ( congruent with 0.1 M). The fact that potassium chloride is unable to reproduce this quenching effect, together with the results obtained on the mutants, suggests a specific binding of the Gdn(+) cation, which involves the E70-K10 ion pair in wt cyt c(551). We propose, therefore, a simple kinetic test to obtain a mechanistic interpretation of nonlinear dependences of DeltaG(w) on GdnHCl concentration on the basis of kinetic refolding experiments in the presence of both denaturants. Study holds ProTherm entries: 15974, 15975, 15976 Extra Details: protein folding; mutants; stability; kinetics; denaturants; guanidinium binding

Submission Details

ID: yixWwpZV4

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:46 p.m.

Version: 1

Publication Details
Gianni S;Brunori M;Travaglini-Allocatelli C,Protein Sci. (2001) Refolding kinetics of cytochrome c(551) reveals a mechanistic difference between urea and guanidine. PMID:11468365
Additional Information

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P
 

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)


Relevant PDB Entries

Structure ID Release Date Resolution Structure Title
1DVV 2000-11-29 SOLUTION STRUCTURE OF THE QUINTUPLE MUTANT OF CYTOCHROME C-551 FROM PSEUDOMONAS AERUGINOSA
2PAC 1993-10-31 SOLUTION STRUCTURE OF FE(II) CYTOCHROME C551 FROM PSEUDOMONAS AERUGINOSA AS DETERMINED BY TWO-DIMENSIONAL 1H NMR
5XEC 2017-08-09 1.1 Heterodimer constructed from PA cyt c551-HT cyt c552 and HT cyt c552-PA cyt c551 chimeric proteins
3X39 2015-04-22 1.5 Domain-swapped dimer of Pseudomonas aeruginosa cytochrome c551
5XED 2017-08-09 1.55 Heterodimer constructed from M61A PA cyt c551-HT cyt c552 and HT cyt c552-PA cyt c551 chimeric proteins
451C 1981-10-02 1.6 STRUCTURE OF CYTOCHROME C551 FROM P. AERUGINOSA REFINED AT 1.6 ANGSTROMS RESOLUTION AND COMPARISON OF THE TWO REDOX FORMS
351C 1981-10-02 1.6 STRUCTURE OF CYTOCHROME C551 FROM P. AERUGINOSA REFINED AT 1.6 ANGSTROMS RESOLUTION AND COMPARISON OF THE TWO REDOX FORMS
2EXV 2006-02-07 1.86 Crystal structure of the F7A mutant of the cytochrome c551 from Pseudomonas aeruginosa

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Cytochrome c-551 P00099 CY551_PSEAE