Soluble Cytochrome b-c1 Complex and the Reconstitution of Succinate-Cytochrome c Reductase

• Published in: The Journal of biological chemistry Vol. 249; no. 15; pp. 4905 - 4910
• Main Authors: Yu, C.A., Yu, L., King, Tsoo E.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 10.08.1974; American Society for Biochemistry and Molecular Biology
• Subjects: Animals; Antimycin A - pharmacology; Binding Sites; Cattle; Cytochrome c Group; Cytochrome Reductases - metabolism; Cytochromes - metabolism; Electrophoresis, Polyacrylamide Gel; Flavins - analysis; Hydroxymercuribenzoates; Iron - analysis; Lipids - analysis; Macromolecular Substances; Mitochondria, Muscle - enzymology; Myocardium; Protein Binding; Protein Conformation; Solubility; Spectrophotometry; Spectrophotometry, Ultraviolet; Succinate Dehydrogenase; Succinates; Ubiquinone - analysis; Ultracentrifugation
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(19)42407-1

The cytochrome b-c1 complex has been “solubilized” and purified to a stage containing 6.5 nmoles of cytochrome b per mg of protein. Seven bands are resolved on a polyacrylamide gel electrophoretic column in sodium dodecyl sulfateβ-mercaptoethanol medium. Five of these seven bands have been identified as cytochromes b and c1 and a non-heme iron protein. The remaining two bands might be associated with these components or, less likely, might be impurities but do not belong to the so-called structural proteins. The cytochrome b-c1 complex is enzymatically active and can reconstitute with soluble succinate dehydrogenase to form an integral entity of antimycin A-sensitive succinate-cytochrome c reductase. The reconstituted reductase shows the same structural and functional characteristics as the intact reductase. The total number of the p-hydroxymercuribenzoate (p-MB) titratable groups in the cytochrome b-c1 complex has been found to be 11 ± 1 moles per mole of cytochrome b. The p-MB-reacted complex is inactive in reconstitution but shows the same catalytic activity in the oxidation of reduced ubiquinone by cytochrome c.