Kriauciunas A, Yu L, Yu C A, Wynn R M, Knaff D B
Department of Chemistry and Biochemistry, Texas Tech University, Lubbock 79409.
Biochim Biophys Acta. 1989 Aug 17;976(1):70-6. doi: 10.1016/s0005-2728(89)80190-2.
A cytochrome bc1 complex, essentially free of bacteriochlorophyll, has been purified from the photosynthetic purple non-sulfur bacterium Rhodospirillum rubrum. The complex catalyzes electron flow from quinol to cytochrome c (turnover number = 75 s-1) that is inhibited by low concentrations of antimycin A and myxothiazol. The complex contains only three peptide subunits: cytochrome b (Mr = 35,000); cytochrome c1 (Mr = 31,000) and the Rieske iron-sulfur protein (Mr = 22,400). Em values (pH 7.4) were measured for cytochrome c1 (+320 mV) and the two hemes of cytochrome b (-33 and -90 mV). Electron flow from quinol to cytochrome c is inhibited when the complex is pre-illuminated in the presence of a ubiquinone photoaffinity analog (azido-Q). During illumination, the azido-Q becomes covalently attached to the cytochrome b peptide and, to a lesser extent, to cytochrome c1.
已从光合紫色非硫细菌深红红螺菌中纯化出一种基本不含细菌叶绿素的细胞色素bc1复合物。该复合物催化从醌醇到细胞色素c的电子流动（周转数 = 75 s-1），此过程受到低浓度抗霉素A和粘噻唑的抑制。该复合物仅包含三个肽亚基：细胞色素b（分子量 = 35,000）；细胞色素c1（分子量 = 31,000）和 Rieske 铁硫蛋白（分子量 = 22,400）。测定了细胞色素c1（+320 mV）和细胞色素b的两个血红素（-33和-90 mV）的Em值（pH 7.4）。当复合物在泛醌光亲和类似物（叠氮-Q）存在下预先光照时，从醌醇到细胞色素c的电子流动受到抑制。在光照期间，叠氮-Q与细胞色素b肽共价结合，并在较小程度上与细胞色素c1共价结合。
