Hutchinson G, Tichelaar W, Weiss H, Leonard K
European Molecular Biology Laboratory, Heidelberg, Federal Republic of Germany.
J Struct Biol. 1990 Mar;103(1):75-88. doi: 10.1016/1047-8477(90)90088-t.
The isolated and water-soluble complex of subunits I and II (core proteins) of ubiquinone:cytochrome c reductase from Neurospora mitochondria forms filaments below pH 6.0. Three independent helical reconstructions of single filaments were compared with the 3-D reconstruction of the native enzyme. A model for the helix is proposed in which the core complex dimers are arranged radially with the face which is proximal to the membrane in the native enzyme on the outside of the helix. The dimension of the core complex dimer perpendicular to the helix axis (70 A) provides an independent estimate of the height of the core complex to that obtained previously from cytochrome reductase crystals. The results of STEM mass measurement and the helical model give a mass per repeating unit of 90 kDa, which would indicate that the monomeric core complex consists of one 45-kDa and one 50-kDa subunit.
细胞色素c还原酶的亚基I和II（核心蛋白）的分离且水溶性复合物在pH 6.0以下形成细丝。将单根细丝的三个独立螺旋重建与天然酶的三维重建进行了比较。提出了一种螺旋模型，其中核心复合物二聚体呈放射状排列，在天然酶中靠近膜的面位于螺旋外侧。核心复合物二聚体垂直于螺旋轴的尺寸（70埃）提供了对核心复合物高度的独立估计，这与先前从细胞色素还原酶晶体获得的估计值一致。扫描透射电子显微镜质量测量结果和螺旋模型给出每个重复单元的质量为90 kDa，这表明单体核心复合物由一个45 kDa和一个50 kDa的亚基组成。
