Kinetic barriers to the folding of horse cytochrome C in the reduced state.


Abstract

To determine the kinetic barrier in the folding of horse cytochrome c, a CO-liganded derivative of cytochrome c, called carbonmonoxycytochrome c, has been prepared by exploiting the thermodynamic reversibility of ferrocytochrome c unfolding induced by guanidinium hydrochloride (GdnHCl), pH 7. The CO binding properties of unfolded ferrocytochrome c, studied by 13C NMR and optical spectroscopy, are remarkably similar to those of native myoglobin and isolated chains of human hemoglobin. Equilibrium unfolding transitions of ferrocytochrome c in the presence and the absence of CO observed by both excitation energy transfer from the lone tryptophan to the ferrous heme and far-UV circular dichroism (CD) indicate no accumulation of structural intermediates to a detectable level. Values of thermodynamic parameters obtained by two-state analysis of fluorescence transitions are DeltaG(H2O) = 11.65(+/-1.13) kcal x mol(-1) and C(m) = 3.9(+/-0.1) M GdnHCl in the presence of CO, and DeltaG(H2O)=19.3(+/-0.5) kcal x mol(-1) and C(m) = 5.1(+/-0.1) M GdnHCl in the absence of CO, indicating destabilization of ferrocytochrome c by approximately 7.65 kcal x mol(-1) due to CO binding. The native states of ferrocytochrome c and carbonmonoxycytochrome c are nearly identical in terms of structure and conformation except for the Fe2+-M80 --> Fe2+-CO replacement. Folding and unfolding kinetics as a function of GdnHCl, studied by stopped-flow fluorescence, are significantly different for the two proteins. Both refold fast, but carbonmonoxycytochrome c refolds 2-fold faster (tau = 1092 micros at 10 degrees C) than ferrocytochrome c. Linear extrapolation of the folding rates to the ordinate of the chevron plot projects this value of tau to 407 micros. The unfolding rate of the former in water, estimated by extrapolation, is faster by more than 10 orders of magnitude. Significant differences are also observed in rate-denaturant gradients in the chevron. Formation and disruption of the Fe2+-M80 coordination contact clearly impose high-energy kinetic barriers to folding and unfolding of ferrocytochrome c. The unfolding barrier due to the Fe2+-M80 bond provides sufficient kinetic stability to the native state of ferrocytochrome c to perform its physiological function as an electron donor. Study holds ProTherm entries: 15654, 15655, 15656, 15657 Extra Details: kinetic barrier; thermodynamic reversibility; folding rate; electron donor

Submission Details

ID: uUd8fZSv

Submitter: Connie Wang

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

Version: 1

Publication Details
Bhuyan AK;Kumar R,Biochemistry (2002) Kinetic barriers to the folding of horse cytochrome C in the reduced state. PMID:12379125
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
1LC2 2003-06-03 Solution Structure Of Reduced Horse Heart Cytochrome c in 30% Acetonitrile Solution, NMR 30 Structures
1I5T 2001-03-21 SOLUTION STRUCTURE OF CYANOFERRICYTOCHROME C
1LC1 2003-06-03 Solution Structure Of Reduced Horse Heart Cytochrome c in 30% Acetonitrile Solution, NMR Minimized Average Structure
1FI9 2000-08-23 SOLUTION STRUCTURE OF THE IMIDAZOLE COMPLEX OF CYTOCHROME C
1OCD 1997-06-16 CYTOCHROME C (OXIDIZED) FROM EQUUS CABALLUS, NMR, MINIMIZED AVERAGE STRUCTURE
1AKK 1997-09-17 SOLUTION STRUCTURE OF OXIDIZED HORSE HEART CYTOCHROME C, NMR, MINIMIZED AVERAGE STRUCTURE
2FRC 1997-07-29 CYTOCHROME C (REDUCED) FROM EQUUS CABALLUS, NMR, MINIMIZED AVERAGE STRUCTURE
1GIW 1998-12-09 SOLUTION STRUCTURE OF REDUCED HORSE HEART CYTOCHROME C, NMR, MINIMIZED AVERAGE STRUCTURE
1M60 2002-08-07 Solution Structure of Zinc-substituted cytochrome c
2GIW 1998-12-09 SOLUTION STRUCTURE OF REDUCED HORSE HEART CYTOCHROME C, NMR, 40 STRUCTURES
5ZKV 2019-05-22 Solution structure of molten globule state of L94G mutant of horse cytochrome-c
1FI7 2000-08-23 Solution structure of the imidazole complex of cytochrome C
2N3B 2015-10-28 Structure of oxidized horse heart cytochrome c encapsulated in reverse micelles
5C0Z 2016-09-21 1.12 The structure of oxidized rat cytochrome c at 1.13 angstroms resolution
5DF5 2016-09-14 1.3 The structure of oxidized rat cytochrome c (T28E) at 1.30 angstroms resolution.
5C9M 2016-09-21 1.36 The structure of oxidized rat cytochrome c (T28A) at 1.362 angstroms resolution.
2B4Z 2005-10-11 1.5 Crystal structure of cytochrome C from bovine heart at 1.5 A resolution.
6FF5 2018-03-21 1.74 X-ray structure of bovine heart cytochrome c at high ionic strength
3O1Y 2012-01-25 1.75 Electron transfer complexes: Experimental mapping of the redox-dependent cytochrome c electrostatic surface
3WUI 2014-07-16 1.8 Dimeric horse cytochrome c formed by refolding from molten globule state
1WEJ 1998-12-09 1.8 IGG1 FAB FRAGMENT (OF E8 ANTIBODY) COMPLEXED WITH HORSE CYTOCHROME C AT 1.8 A RESOLUTION
3WC8 2013-12-11 1.8 Dimeric horse cytochrome c obtained by refolding with desalting method
3O20 2012-01-25 1.9 Electron transfer complexes:experimental mapping of the Redox-dependent Cytochrome C electrostatic surface
1HRC 1994-11-01 1.9 HIGH-RESOLUTION THREE-DIMENSIONAL STRUCTURE OF HORSE HEART CYTOCHROME C
2YBB 2011-10-19 19.0 Fitted model for bovine mitochondrial supercomplex I1III2IV1 by single particle cryo-EM (EMD-1876)
5IY5 2017-01-11 2.0 Electron transfer complex of cytochrome c and cytochrome c oxidase at 2.0 angstrom resolution
1CRC 1996-03-08 2.08 CYTOCHROME C AT LOW IONIC STRENGTH
3NBT 2010-07-14 2.1 Crystal structure of trimeric cytochrome c from horse heart
4NFG 2014-09-24 2.11 K13R mutant of horse cytochrome c and yeast cytochrome c peroxidase complex
4RSZ 2015-01-14 2.19 The X-ray structure of the Primary Adduct formed in the Reaction between Cisplatin and Cytochrome c
3NBS 2010-07-14 2.2 Crystal structure of dimeric cytochrome c from horse heart
1KTD 2002-05-01 2.4 CRYSTAL STRUCTURE OF CLASS II MHC MOLECULE IEK BOUND TO PIGEON CYTOCHROME C PEPTIDE
1U75 2004-09-28 2.55 Electron Transfer Complex between Horse Heart Cytochrome c and Zinc-Porphyrin Substituted Cytochrome c Peroxidase
2PCB 1993-07-15 2.8 CRYSTAL STRUCTURE OF A COMPLEX BETWEEN ELECTRON TRANSFER PARTNERS, CYTOCHROME C PEROXIDASE AND CYTOCHROME C
3JBT 2015-11-18 3.8 Atomic structure of the Apaf-1 apoptosome
5JUY 2016-10-19 4.1 Active human apoptosome with procaspase-9
5WVE 2017-02-08 4.4 Apaf-1-Caspase-9 holoenzyme
3J2T 2013-04-10 9.5 An improved model of the human apoptosome

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