Kawamoto M, Kubota T, Matsunaga T, Fukuyama K, Matsubara H, Shinzawa-Itoh K, Yoshikawa S
Department of Biology, Faculty of Science, Osaka University, Japan.
J Mol Biol. 1994 Nov 25;244(2):238-41. doi: 10.1006/jmbi.1994.1722.
Two new crystal forms of the cytochrome bc1 complex (ubiquinol:ferricytochrome c oxidoreductase, EC. 1.10.2.2) from bovine heart mitochondria were obtained by the batch method with polyethylene glycol 4000 as the precipitant, when buffer was exchanged from Tris-HCl to potassium phosphate. The first crystal form belongs to the hexagonal space group P61 or P6(5) with unit-cell constants of a = b = 131 A and c = 720 A. The reproducibility of crystallization and the quality of this crystal form were improved by an addition of ZnCl2 to the protein solution. The second crystal form, obtained from the enzyme preparation purified by crystallization, belongs to the tetragonal space group P4(1) or P4(3) with unit-cell constants of a = b = 190 A and c = 445 A. Both crystals diffracted X-rays to 6.5 A resolution and gave sharper diffraction spots than the previous monoclinic form. X-ray intensity data to 8.0 A resolution for the hexagonal crystal and to 7.0 A resolution for the tetragonal one were collected with synchrotron radiation.
当缓冲液从Tris-HCl换成磷酸钾时，采用聚乙二醇4000作为沉淀剂的分批法，从牛心线粒体中获得了细胞色素bc1复合物（泛醇：铁细胞色素c氧化还原酶，EC. 1.10.2.2）的两种新晶型。第一种晶型属于六方空间群P61或P6(5)，晶胞常数为a = b = 131 Å，c = 720 Å。通过向蛋白质溶液中添加ZnCl2，提高了结晶的重现性和这种晶型的质量。第二种晶型是从通过结晶纯化的酶制剂中获得的，属于四方空间群P4(1)或P4(3)，晶胞常数为a = b = 190 Å，c = 445 Å。两种晶体的X射线衍射分辨率均达到6.5 Å，并且比之前的单斜晶型给出的衍射斑点更清晰。利用同步辐射收集了六方晶体8.0 Å分辨率和四方晶体7.0 Å分辨率的X射线强度数据。
