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Equilibrium unfolding of a small low-potential cytochrome, cytochrome c553 from Desulfovibrio vulgaris
- Source :
- Scopus-Elsevier
- Publication Year :
- 1999
- Publisher :
- Cold Spring Harbor Laboratory Press, 1999.
-
Abstract
- To understand general aspects of stability and folding of c-type cytochromes, we have studied the folding characteristics of cytochrome c553 from Desulfovibrio vulgaris (Hildenborough). This cytochrome is structurally similar but lacks sequence homology to other heme proteins; moreover, it has an abnormally low reduction potential. Unfolding of oxidized and reduced cytochrome c553 by guanidine hydrochloride (GuHCl) was monitored by circular dichroism (CD) and Soret absorption; the same unfolding curves were obtained with both methods supporting that cytochrome c553 unfolds by an apparent two-state process. Reduced cytochrome c553 is 7(3) kJ/mol more stable than the oxidized form; accordingly, the reduction potential of unfolded cytochrome c553 is 100(20) mV more negative than that of the folded protein. In contrast to many other unfolded cytochrome c proteins, upon unfolding at pH 7.0 both oxidized and reduced heme in cytochrome c553 become high-spin. The lack of heme misligation in unfolded cytochrome c553 implies that its unfolded structure is less constrained than those of cytochromes c with low-spin, misligated hemes.
- Subjects :
- Protein Denaturation
Hemeprotein
biology
Cytochrome
Cytochrome b
Cytochrome c peroxidase
Stereochemistry
Cytochrome c
Circular Dichroism
Equilibrium unfolding
Cytochrome c Group
Heme
Biochemistry
chemistry.chemical_compound
chemistry
Coenzyme Q – cytochrome c reductase
biology.protein
Thermodynamics
Desulfovibrio vulgaris
Molecular Biology
Oxidation-Reduction
Research Article
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Journal :
- Scopus-Elsevier
- Accession number :
- edsair.doi.dedup.....0afcb2976560a3588e5fec8f93e6ccad