Dimeric horse cytochrome c obtained by refolding with desalting method

Experimental Data Snapshot

  • Resolution: 1.80 Å
  • R-Value Free: 0.208 
  • R-Value Work: 0.169 
  • R-Value Observed: 0.171 

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Formation of Oligomeric Cytochrome c during Folding by Intermolecular Hydrophobic Interaction between N- and C-Terminal alpha-Helices

Parui, P.P.Deshpande, M.S.Nagao, S.Kamikubo, H.Komori, H.Higuchi, Y.Kataoka, M.Hirota, S.

(2013) Biochemistry 52: 8732-8744

  • DOI: https://doi.org/10.1021/bi400986g
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    We have previously shown that horse cytochrome c (cyt c) forms oligomers by domain swapping its C-terminal α-helix when interacting with ethanol. Although folding of cyt c has been studied extensively, formation of domain-swapped oligomers of cyt c during folding has never been reported. We found that domain-swapped oligomeric cyt c is produced during refolding from its guanidinium ion-induced unfolded state at high protein concentrations and low temperatures. The obtained dimer exhibited a domain-swapped structure exchanging the C-terminal α-helical region between molecules. The extent of dimer formation decreased significantly for the folding of C-terminal cyt c mutants with reduced hydrophobicity achieved by replacement of hydrophobic residues with Gly in the C-terminal region, whereas a large amount of heterodimers was generated for the folding of a mixture of N- and C-terminal mutants. These results show that cyt c oligomers are formed through intermolecular hydrophobic interaction between the N- and C-terminal α-helices during folding. A slow phase (4-5 s) was observed in addition to a 400-500 ms phase during folding of a high concentration of cyt c in the presence of 1.17 M guanidine hydrochloride. The fast phase is attributed to the intramolecular ligand exchange process, and we attribute the slow phase to the ligand exchange process in oligomers. These results show that it is important to consider formation of domain-swapped oligomeric proteins when folding at high protein concentrations.

  • Organizational Affiliation

    Graduate School of Materials Science, Nara Institute of Science and Technology , 8916-5 Takayama, Ikoma, Nara 630-0192, Japan.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Cytochrome c104Equus caballusMutation(s): 0 
Find proteins for P00004 (Equus caballus)
Explore P00004 
Go to UniProtKB:  P00004
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP00004
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.80 Å
  • R-Value Free: 0.208 
  • R-Value Work: 0.169 
  • R-Value Observed: 0.171 
  • Space Group: C 2 2 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 60.815α = 90
b = 93.476β = 90
c = 36.241γ = 90
Software Package:
Software NamePurpose
HKL-2000data collection
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2013-12-11
    Type: Initial release
  • Version 1.1: 2013-12-18
    Changes: Database references
  • Version 2.0: 2019-10-02
    Changes: Atomic model, Data collection, Derived calculations, Non-polymer description, Structure summary
  • Version 2.1: 2023-11-08
    Changes: Data collection, Database references, Derived calculations, Refinement description