Lambert O, Boisset N, Taveau J C, Lamy J N
Laboratoire des Protéines Complexes, Université François Rabelais, Tours, France.
Arch Biochem Biophys. 1995 Feb 1;316(2):950-9. doi: 10.1006/abbi.1995.1126.
The three-dimensional reconstruction of Sepia hemocyanin from randomly oriented native molecules was carried out by the method of the random conical tilt series on a frozen-hydrated specimen. As other molluscan hemocyanins, the molecule resembles a hollow cylinder or pentahedron composed of five dimeric subunits. Each dimeric subunit, composed of 16 functional units, comprises one wall oblique unit made up of 12 functional units and one arch made up of four functional units. The five wall oblique units are separated from each other by five oblique clefts bridged by the five arches, formerly termed collar structures. Each arch is composed of two types of functional units that are probably Soe, a functional unit absent in Octopus hemocyanin, and Soh, the C-terminal functional unit of the polypeptide chain. The architecture of the arches and their intramolecular location in front of the edges of the pentahedron are strongly reminiscent of the arches of Octopus hemocyanin. The D5 point-group symmetry of the molecule suggests that the orientation of the polypeptide chains is antiparallel as in Octopus hemocyanin. Several models of architecture compatible with these results are designed.
利用随机锥形倾斜系列方法，对冷冻水合标本上随机取向的天然乌贼血蓝蛋白分子进行了三维重建。与其他软体动物血蓝蛋白一样，该分子类似于由五个二聚体亚基组成的空心圆柱体或五面体。每个二聚体亚基由16个功能单元组成，包括一个由12个功能单元组成的壁斜单元和一个由4个功能单元组成的拱。五个壁斜单元由五个由拱桥接的斜裂彼此分开，这些拱以前称为环结构。每个拱由两种类型的功能单元组成，可能是章鱼血蓝蛋白中不存在的功能单元Soe和多肽链的C端功能单元Soh。拱的结构及其在五面体边缘前方的分子内位置强烈让人联想到章鱼血蓝蛋白的拱。分子的D5点群对称性表明，多肽链的取向与章鱼血蓝蛋白一样是反平行的。设计了几个与这些结果相符的结构模型。
