Protein folding in classical perspective: folding of horse cytochrome c.


Proteins meet with the stipulations of Levinthal. Two test tube variants of ferrocytochrome c (ferrocyt c) whose thermodynamic stabilities are vastly different refold to the same global minimum under a given final native condition, and they do so quickly at rates that do not reflect a strong dependence on the thermodynamic driving force. The transition-state ensemble is more unfolded-like, and the folding barrier offered is energetically sizable. The experiments involve neutral- (pH 7) and alkaline ferrocyt c pH (12.7), whose aqueous stabilities are 18 (+/-0.3) and 3 (+/-0.5) kcal mol(-)(1), respectively. But the large disparity in thermodynamic stability is not strongly reflected in their refolding rates. Cross-pH studies, where GdnHCl-unfolded states of neutral- and alkaline ferrocyt c are allowed to refold to the same final pH and denaturant concentration, indicate that the refolding rates are largely independent of the stability, configuration, ionization, and solvation of the initial unfolded state. Also, burst relaxation signals in cross-pH refolding runs show the same quantitative dependence on GdnHCl, suggesting that the earliest relaxation or reconfiguration of the chains must be the same and is independent of the initial equilibrium unfolded state. Analyses along the classical line indicate an early transition state where much less than a third of the protein surface that is buried in the native state becomes buried. The barrier energy is of the order of 10 k(B)T. The results, apparently inconsistent with the predictions of the funnel model, afford a mechanistic description of folding in which the folding time of small single-domain proteins is set by the time needed for the denatured polypeptide to search-find a nativelike topology. Study holds ProTherm entries: 18672, 18673 Extra Details: transition-state ensemble; folding barrier; refolding rates; funnel model

Submission Details

ID: Gy2GaPoY3

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:50 p.m.

Version: 1

Publication Details
Bhuyan AK;Rao DK;Prabhu NP,Biochemistry (2005) Protein folding in classical perspective: folding of horse cytochrome c. PMID:15723547
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
2B4Z 2005-09-27T00:00:00+0000 1.5 Crystal structure of cytochrome C from bovine heart at 1.5 A resolution.
2YBB 2011-03-02T00:00:00+0000 19.0 Fitted model for bovine mitochondrial supercomplex I1III2IV1 by single particle cryo-EM (EMD-1876)
3J2T 2012-12-23T00:00:00+0000 9.5 An improved model of the human apoptosome
5C0Z 2015-06-12T00:00:00+0000 1.12 The structure of oxidized rat cytochrome c at 1.13 angstroms resolution
5C9M 2015-06-28T00:00:00+0000 1.36 The structure of oxidized rat cytochrome c (T28A) at 1.362 angstroms resolution.
5DF5 2015-08-26T00:00:00+0000 1.3 The structure of oxidized rat cytochrome c (T28E) at 1.30 angstroms resolution.
5JUY 2016-05-10T00:00:00+0000 4.1 Active human apoptosome with procaspase-9
6FF5 2018-01-03T00:00:00+0000 1.74 X-ray structure of bovine heart cytochrome c at high ionic strength
6N1O 2018-11-09T00:00:00+0000 1.55 Oxidized rat cytochrome c mutant (S47E)

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
91.3 Cytochrome c P00021 CYC_COLLI
92.2 Cytochrome c P00020 CYC_ANAPL
92.3 Cytochrome c P81280 CYC_ALLMI
90.5 Cytochrome c Q52V10 CYC_SAISC
93.3 Cytochrome c P00012 CYC_MIRLE
93.3 Cytochrome c Q52V09 CYC_CEPBA
93.3 Cytochrome c P00013 CYC_MINSC
93.3 Cytochrome c P00014 CYC_MACGI
94.3 Cytochrome c P00011 CYC_CANLF
94.3 Cytochrome c P62898 CYC_RAT
94.3 Cytochrome c P00008 CYC_RABIT
94.3 Cytochrome c P62897 CYC_MOUSE
95.2 Cytochrome c P68098 CYC_LAMGU
95.2 Cytochrome c P68100 CYC_ESCRO
95.2 Cytochrome c P68099 CYC_CAMDR
94.3 Cytochrome c P00007 CYC_HIPAM
97.1 Cytochrome c P62896 CYC_SHEEP
97.1 Cytochrome c P62895 CYC_PIG
97.1 Cytochrome c P62894 CYC_BOVIN
99.0 Cytochrome c P68096 CYC_EQUBU
99.0 Cytochrome c P68097 CYC_EQUAS
100.0 Cytochrome c P00004 CYC_HORSE
90.3 Cytochrome c B4USV4 CYC_OTOGA