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Electron-transfer pathways in the heme and quinone-binding domain of complex II (succinate dehydrogenase).
- Source :
-
Biochemistry [Biochemistry] 2014 Mar 18; Vol. 53 (10), pp. 1637-46. Date of Electronic Publication: 2014 Mar 03. - Publication Year :
- 2014
-
Abstract
- Single electron transfers have been examined in complex II (succinate:ubiquinone oxidoreductase) by the method of pulse radiolysis. Electrons are introduced into the enzyme initially at the [3Fe-4S] and ubiquinone sites followed by intramolecular equilibration with the b heme of the enzyme. To define thermodynamic and other controlling parameters for the pathways of electron transfer in complex II, site-directed variants were constructed and analyzed. Variants at SdhB-His207 and SdhB-Ile209 exhibit significantly perturbed electron transfer between the [3Fe-4S] cluster and ubiquinone. Analysis of the data using Marcus theory shows that the electronic coupling constants for wild-type and variant enzyme are all small, indicating that electron transfer occurs by diabatic tunneling. The presence of the ubiquinone is necessary for efficient electron transfer to the heme, which only slowly equilibrates with the [3Fe-4S] cluster in the absence of the quinone.
- Subjects :
- Electron Transport
Electron Transport Complex II chemistry
Electron Transport Complex II genetics
Escherichia coli chemistry
Escherichia coli genetics
Escherichia coli Proteins chemistry
Escherichia coli Proteins genetics
Heme chemistry
Mutagenesis, Site-Directed
Protein Binding
Protein Structure, Tertiary
Ubiquinone chemistry
Ubiquinone metabolism
Electron Transport Complex II metabolism
Escherichia coli enzymology
Escherichia coli Proteins metabolism
Heme metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1520-4995
- Volume :
- 53
- Issue :
- 10
- Database :
- MEDLINE
- Journal :
- Biochemistry
- Publication Type :
- Academic Journal
- Accession number :
- 24559074
- Full Text :
- https://doi.org/10.1021/bi401630m