Macrofiber structure and the dynamics of sickle cell hemoglobin crystallization.
Macrofiber structure and the dynamics of sickle cell hemoglobin crystallization.
复制标题
粗纤维结构和镰状细胞血红蛋白结晶动力学。
DOI：
10.1016/0022-2836(84)90050-0
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发表时间：
1984
影响因子：
5.6
通讯作者：
Josephs,R
中科院分区：
文献类型：
--
作者：
Potel,MJ;Wellems,TE;Vassar,RJ;Deer,B;Josephs,R
脱氧血红蛋白S的纤维通过涉及多种中间结构的机制进行自发结晶。这些中间结构与纤维和晶体一样，由以不同构型排列的血红蛋白S分子的Wishner-Love双链组成。连接纤维和晶体的关键中间体之一的结构，称为粗纤维，已经通过各种分析方法进行了研究。分析结果表明，参与纤维向晶体转变的中间体具有许多共同的结构特征。傅立叶分析的电子显微照片的大纤维证实，它们是由Wishner-Love双股血红蛋白分子。长纤维横截面的电子显微照片显示，在长纤维中的双股的安排类似于在晶体的a轴投影的显微照片中看到的。这种取向提供了双链的端视图，其表现为成对的哑铃状团块。由于双股围绕颗粒轴的扭曲，结构细节朝着颗粒边缘逐渐变得不那么明显。大纤维的连续切片证实了这些粒子确实绕着它们的轴旋转。粒子的扭曲是右手的，其平均螺距为10，000 μ m。旋转对300至400微米厚的粗纤维横截面外观的影响可以通过旋转15 °的间轴晶体投影来模拟。通过直接观察显微照片，可以很容易地确定粗纤维和晶体中双股的相对极性。在粗纤维和晶体中，它们都呈反平行排列。根据这些观察，我们得出结论，粗纤维的结晶涉及双股的解扭和排列。
Fibers of deoxyhemoglobin S undergo spontaneous crystallization by a mechanism involving a variety of intermediate structures. These intermediate structures, in common with the fiber and crystal, consist of Wishner-Love double strands of hemoglobin S molecules arranged in different configurations. The structure of one of the key intermediates linking the fiber and crystal, called a macrofiber, has been studied by a variety of analytical procedures. The results of the analysis indicate that the intermediates involved in the fiber to crystal transition have many common structural features. Fourier analysis of electron micrographs of macrofibers confirms that they are composed of Wishner-Love double strands of hemoglobin molecules. Electron micrographs of macrofiber cross-sections reveal that the arrangement of the double strands in macrofibers resembles that seen in micrographs of theaaxis projection of the crystal. This orientation provides an end-on view of the double strands which appear as paired dumb-bell-like masses. The structural detail becomes progressively less distinct towards the edge of the particle due to twisting of the double strands about the particle axis. Serial sections of macrofibers confirm that these particles do indeed rotate about their axes. The twist of the particle is right handed and its average pitch is 10,000 Å. The effect of rotation on the appearance of macrofiber cross-sections 300 to 400 Å thick can be simulated by a 15 ° rotation of anaaxis crystal projection. The relative polarity of the double strands in macrofibers and crystals can be determined easily by direct inspection of the micrographs. In both macrofibers and crystals they are in an anti-parallel array.On the basis of these observations we conclude that crystallization of macrofibers involves untwisting and alignment of the double strands.