Quaternary structure of Octopus vulgaris hemocyanin. Three-dimensional reconstruction from frozen-hydrated specimens and intramolecular location of functional units Ove and Ovb.
Quaternary structure of Octopus vulgaris hemocyanin. Three-dimensional reconstruction from frozen-hydrated specimens and intramolecular location of functional units Ove and Ovb.
复制标题
普通章鱼血蓝蛋白的四级结构。
DOI：
10.1006/jmbi.1994.1269
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发表时间：
1994
影响因子：
5.6
通讯作者：
Lamy,JN
中科院分区：
文献类型：
--
作者：
Lambert,O;Boisset,N;Penczek,P;Lamy,J;Taveau,JC;Frank,J;Lamy,JN
在低剂量条件下，用透射电子显微镜对章鱼血蓝蛋白的冷冻水化样品在0°和40°倾角下成像。通过随机锥形倾斜系列的方法进行三维重建，产生了一个三维体积，其中应用了D5对称性。检查连续切片的体积和表面表示在不同的阈值允许五个拱含有功能unitOvgto定位在interdimerical亚基沟。在另一组实验中，使用特异性多克隆抗体来标记圆筒壁中的功能单位。免疫复合物的负染观察显示Ovbis位于功能单位的外层，Ov位于功能单位的内层。这些结果表明，在圆筒壁的多肽链的方向可能只是部分反平行。提出了一种具有以下特征的四级结构模型：（1）功能单元的外部层包含来自单个多肽链的每个单元（Ova-d）;（2）内部层包含来自每个多肽链的两个功能单元（Ove-f）;（3）二聚体亚基拱连接位于每个多肽链中的单个功能单元（Ovg）的两个拷贝。
A frozen-hydrated sample ofOctopus vulgarishemocyanin was imaged at 0° and 40° tilt angle under low dose conditions by transmission electron microscopy. A three-dimensional reconstruction by the method of random conical tilt series produced a three-dimensional volume to which a D5symmetry was applied. Examination of serial sections in the volume and surface representation at various threshold allowed the five arches containing functional unitOvgto be localized at the interdimeric subunit groove. In another set of experiments specific polyclonal antibodies were used to label functional unitsOvbandOvein the cylinder wall. The observation of the negatively stained immunocomplexes showed thatOvbis located in the external tiers of functional units andOvein the internal tier. These results suggest that the direction of the polypeptide chains in the cylinder wall may be only partially antiparallel. A model of the quaternary structure is proposed with the following features: (1) the external tiers of functional units comprise four units each (Ova-d) coming from a single polypeptide chain; (2) the internal tier comprises two functional units from each polypeptide chain (Ove-f); (3) the interdimeric subunit arches connect the two copies of a single functional unit (Ovg) located in each polypeptide chain.