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Molecular conversion between monomeric and dimeric states of the mitochondrial cytochrome b-c1 complex: isolation of active monomers
- Source :
- Archives of biochemistry and biophysics. 236(2)
- Publication Year :
- 1985
-
Abstract
- Bovine heart cytochrome b-c1 complex dispersed in 0.1% dodecylmaltoside, 10 mM Tris-HCl (pH 7.4), was subjected to filtration on Ultrogel AcA 34 columns. Apparent Mr values of about 400,000 and 170,000 were estimated for the enzyme-detergent complex in the presence and absence of 50 mM KCl, respectively. Similar Mr values (about 390,000 and 160,000) were obtained after sucrose gradient centrifugation of the b-c1 complex species isolated using Ultrogel filtration. Both species contained eight polypeptides, as in the original cytochrome b-c1 complex. The experiments suggest that the two species represent a dimer and a monomer of the b-c1 complex. The molecular conversion between the monomeric and dimeric state of the enzyme was found to be reversible. Both monomers and dimers of the b-c1 complex were competent to catalyze QH2:cytochrome c reductase activity with approximately the same maximal velocity. The finding that both molecular forms of the enzyme appear equally active does not support functional models based exclusively on a dimeric b-c1 complex.
- Subjects :
- Hemeprotein
Cytochrome
Chemical Phenomena
Stereochemistry
Macromolecular Substances
Dimer
Detergents
Biophysics
Biochemistry
Mitochondria, Heart
chemistry.chemical_compound
Electron Transport Complex III
Multienzyme Complexes
Centrifugation, Density Gradient
Animals
NADH, NADPH Oxidoreductases
Quinone Reductases
Molecular Biology
Differential centrifugation
chemistry.chemical_classification
biology
Spectrum Analysis
Biological activity
Chemistry
Kinetics
Monomer
Enzyme
chemistry
Coenzyme Q – cytochrome c reductase
biology.protein
Chromatography, Gel
Cattle
Subjects
Details
- ISSN :
- 00039861
- Volume :
- 236
- Issue :
- 2
- Database :
- OpenAIRE
- Journal :
- Archives of biochemistry and biophysics
- Accession number :
- edsair.doi.dedup.....16677484ce75a859985f5d256244344f