3wui | pdb_00003wui
Dimeric horse cytochrome c formed by refolding from molten globule state
Structural highlights
Function[CYC_HORSE] Electron carrier protein. The oxidized form of the cytochrome c heme group can accept an electron from the heme group of the cytochrome c1 subunit of cytochrome reductase. Cytochrome c then transfers this electron to the cytochrome oxidase complex, the final protein carrier in the mitochondrial electron-transport chain. Plays a role in apoptosis. Suppression of the anti-apoptotic members or activation of the pro-apoptotic members of the Bcl-2 family leads to altered mitochondrial membrane permeability resulting in release of cytochrome c into the cytosol. Binding of cytochrome c to Apaf-1 triggers the activation of caspase-9, which then accelerates apoptosis by activating other caspases (By similarity). Publication Abstract from PubMedMany 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 SO42- (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 alpha-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. Formation of Domain-Swapped Oligomer of Cytochrome c from Its Molten Globule State Oligomer.,Deshpande MS, Parui PP, Kamikubo H, Yamanaka M, Nagao S, Komori H, Kataoka M, Higuchi Y, Hirota S Biochemistry. 2014 Jul 9. PMID:24981551[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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