title: Formation of domain-swapped oligomer of cytochrome C from its molten globule state oligomer.
abstract: Many proteins, including cytochrome c (cyt c), have been shown to form domain-swapped oligomers, but the factors governing the oligomerization process remain unrevealed. We obtained oligomers of cyt c by refolding cyt c from its acid molten globule state to neutral pH state under high protein and ion concentrations. The amount of oligomeric cyt c obtained depended on the nature of the anion (chaotropic or kosmotropic) in the solution: ClO4(-) (oligomers, 11% ± 2% (heme unit)), SCN(-) (10% ± 2%), I(-) (6% ± 2%), NO3(-) (3% ± 1%), Br(-) (2% ± 1%), Cl(-) (2% ± 1%), and SO4(2-) (3% ± 1%) for refolding of 2 mM cyt c (anion concentration 125 mM). Dimeric cyt c obtained by refolding from the molten globule state exhibited a domain-swapped structure, in which the C-terminal α-helices were exchanged between protomers. According to small-angle X-ray scattering measurements, approximately 25% of the cyt c molecules were dimerized in the molten globule state containing 125 mM ClO4(-). These results indicate that a certain amount of molten globule state oligomers of cyt c convert to domain-swapped oligomers during refolding and that the intermolecular interactions necessary for domain swapping are present in the molten globule state.
authors: Graduate School of Materials Science, Nara Institute of Science and Technology , 8916-5 Takayama, Ikoma, Nara 630-0192, Japan.
authors: Megha Subhash
authors: MS
authors: Deshpande
authors: Partha Pratim
authors: PP
authors: Parui
authors: Hironari
authors: H
authors: Kamikubo
authors: Masaru
authors: M
authors: Yamanaka
authors: Satoshi
authors: S
authors: Nagao
authors: Hirofumi
authors: H
authors: Komori
authors: Mikio
authors: M
authors: Kataoka
authors: Yoshiki
authors: Y
authors: Higuchi
authors: Shun
authors: S
authors: Hirota
mesh_terms: D045304:Cytochromes c / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D017510:Protein Folding; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary
chemical_list: D045304:Cytochromes c