5dfs
From Proteopedia
Crystal structure of Spider Monkey Cytochrome C at 1.15 Angstrom
Structural highlights
Function[CYC_ATESP] 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 PubMedThe hypothesis that the recent rapid evolution of primate cytochromes c, which primarily involves residues in the least stable Omega-loop (Omega-loop C, residues 40-57), stabilizes the heme crevice of cytochrome c relative to other mammals, is tested. To accomplish this goal, we have compared the properties of human and spider monkey cytochrome c and a set of four variants produced in the process of converting human cytochrome c into spider monkey cytochrome c. The global stability of all variants has been measured by guanidine hydrochloride denaturation. The stability of the heme crevice has been assessed with the alkaline conformational transition. Structural insight into the effects of the five amino acid substitutions needed to convert human cytochrome c into spider monkey cytochrome c is provided by a 1.15A resolution structure of spider monkey cytochrome c. The global stability for all variants is near 9.0kcal/mol at 25 degrees C and pH7, which is higher than that observed for other mammalian cytochromes c. The heme crevice stability is more sensitive to the substitutions required to produce spider monkey cytochrome c with decreases of up to 0.5 units in the apparent pKa of the alkaline conformational transition relative to human cytochrome c. The structure of spider monkey cytochrome c indicates that the Y46F substitution destabilizes the heme crevice by disrupting an extensive hydrogen bond network that connects three surface loops including Omega-loop D (residues 70-85), which contains the Met80 heme ligand. Disruption of a hydrogen bond network in human versus spider monkey cytochrome c affects heme crevice stability.,Goldes ME, Jeakins-Cooley ME, McClelland LJ, Mou TC, Bowler BE J Inorg Biochem. 2015 Dec 31. pii: S0162-0134(15)30156-2. doi:, 10.1016/j.jinorgbio.2015.12.025. PMID:26775610[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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