Equilibrium studies of the effect of difference in sequence homology on the mechanism of denaturation of bovine and horse cytochromes-c.


We have carried out equilibrium studies of the effect of the amino acid residue difference in the primary structure of bovine cytochrome-c (b-cyt-c) and horse cyt-c (h-cyt-c) on the mechanism of their folding <--> unfolding processes at pH 6.0 and 25 degrees C. It has been observed that guanidinium chloride (GdmCl)-induced denaturation of b-cyt-c follows a two-state mechanism and that of h-cyt-c is not a two-state process. This conclusion is reached from the coincidence and non-coincidence of GdmCl-induced transition curves of bovine and horse proteins, respectively, monitored by measurements of absorbance at 405, 530 and 695 nm and circular dichroism (CD) at 222, 416 and 405 nm. These measurements on h-cyt-c in the presence of GdmCl in the concentration range 0.75-2.0 M also suggest that the protein retains all the native far-UV CD but has slightly perturbed tertiary interaction. The intermediate in the presence of these low denaturant concentrations does not have the structural characteristics of a molten globule as judged by the 8-Anilino-1-napthalene sulfonic acid (ANS) binding and near-UV CD experiments. We have also carried out thermal denaturation studies of bovine and horse cyts-c in the presence of GdmCl monitored by absorbance at 405 nm and far-UV CD at 222 nm. The heat-induced denaturation measurements in the presence of the denaturant show (1) that denaturation of b-cyt-c is a two-state process and that of h-cyt-c does not follow a two-state mechanism, and (2) that the enthalpy change on denaturation of both proteins strongly depends on GdmCl concentration. Study holds ProTherm entries: 15736, 15737, 15738, 15739, 15740, 15741, 15742, 15743, 15744, 15745, 15746, 15747, 15748, 15749, 15750, 15751, 15752, 15753, 15754, 15755, 15756, 15757, 15758, 15759, 15760, 15761, 15762, 15763, 15764, 15765, 15766, 15767, 15768, 15769, 15770, 15771, 15772, 15773, 15774, 15775, 15776, 15777, 15778, 15779, 15780, 15781, 15782, 15783, 15784, 15785, 15786, 15787 Extra Details: at molar absorption coefficient e = 405 nm. Even though the unit for 'm' is kJ/mol/M, here the unit is given as the authors assigned. Guanidinium chloride unfolding; Thermal unfolding; Protein stability; Circular dichroism; Molten globule

Submission Details

ID: uLQQjxGv

Submitter: Connie Wang

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

Version: 1

Publication Details
Moza B;Qureshi SH;Ahmad F,Biochim. Biophys. Acta (2003) Equilibrium studies of the effect of difference in sequence homology on the mechanism of denaturation of bovine and horse cytochromes-c. PMID:12637011
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
2AIU 2005-08-01T00:00:00+0000 1.6 Crystal Structure of Mouse Testicular Cytochrome C at 1.6 Angstrom
5C0Z 2015-06-12T00:00:00+0000 1.12 The structure of oxidized rat cytochrome c at 1.13 angstroms resolution
6N1O 2018-11-09T00:00:00+0000 1.55 Oxidized rat cytochrome c mutant (S47E)
5DF5 2015-08-26T00:00:00+0000 1.3 The structure of oxidized rat cytochrome c (T28E) at 1.30 angstroms resolution.
5C9M 2015-06-28T00:00:00+0000 1.36 The structure of oxidized rat cytochrome c (T28A) at 1.362 angstroms resolution.
6FF5 2018-01-03T00:00:00+0000 1.74 X-ray structure of bovine heart cytochrome c at high ionic strength
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
2B4Z 2005-09-27T00:00:00+0000 1.5 Crystal structure of cytochrome C from bovine heart at 1.5 A resolution.

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
90.3 Cytochrome c P21665 CYC_VARVA
90.4 Cytochrome c P00015 CYC2_MOUSE
90.5 Cytochrome c Q640U4 CYC1_XENTR
91.4 Cytochrome c P00022 CYC_CHESE
90.5 Cytochrome c P00019 CYC_STRCA
90.5 Cytochrome c P00018 CYC_DRONO
90.5 Cytochrome c Q5RFH4 CYC_PONAB
90.5 Cytochrome c P99998 CYC_PANTR
90.5 Cytochrome c P99999 CYC_HUMAN
90.5 Cytochrome c Q6WUX8 CYC_GORGO
90.5 Cytochrome c P00017 CYC_APTPA
91.4 Cytochrome c P67882 CYC_MELGA
91.4 Cytochrome c P67881 CYC_CHICK
94.2 Cytochrome c P00020 CYC_ANAPL
91.4 Cytochrome c Q52V08 CYC_MACSY
91.4 Cytochrome c P00002 CYC_MACMU
93.2 Cytochrome c P00021 CYC_COLLI
94.2 Cytochrome c P81280 CYC_ALLMI
91.4 Cytochrome c Q52V10 CYC_SAISC
93.2 Cytochrome c B4USV4 CYC_OTOGA
95.2 Cytochrome c P00013 CYC_MINSC
94.3 Cytochrome c P00014 CYC_MACGI
96.2 Cytochrome c P00012 CYC_MIRLE
96.2 Cytochrome c P00008 CYC_RABIT
96.2 Cytochrome c Q52V09 CYC_CEPBA
100.0 Cytochrome c P00004 CYC_HORSE
97.1 Cytochrome c P00011 CYC_CANLF
97.1 Cytochrome c P62898 CYC_RAT
97.1 Cytochrome c P62897 CYC_MOUSE
99.0 Cytochrome c P68096 CYC_EQUBU
99.0 Cytochrome c P68097 CYC_EQUAS
98.1 Cytochrome c P68098 CYC_LAMGU
98.1 Cytochrome c P68100 CYC_ESCRO
98.1 Cytochrome c P68099 CYC_CAMDR
97.1 Cytochrome c P00007 CYC_HIPAM
100.0 Cytochrome c P62896 CYC_SHEEP
100.0 Cytochrome c P62895 CYC_PIG
100.0 Cytochrome c P62894 CYC_BOVIN