Polymorphic assemblies of double strands of sickle cell hemoglobin. Manifold pathways of deoxyhemoglobin S crystallization.
Polymorphic assemblies of double strands of sickle cell hemoglobin. Manifold pathways of deoxyhemoglobin S crystallization.
复制标题
镰状细胞血红蛋白双链的多态性组装。
DOI：
10.1016/0022-2836(81)90464-2
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发表时间：
1981
影响因子：
5.6
通讯作者：
Josephs,R
中科院分区：
文献类型：
--
作者：
Wellems,TE;Vassar,RJ;Josephs,R
镰状细胞血红蛋白的结晶通过不同的途径进行，这取决于pH值和结晶环境的离子组成。通路的不同之处在于，在纤维形成后，它们结合成不同的中间产物，然后结晶。我们称之为“高pH值”和“低pH值”途径。在高pH值和低pH值途径之间的转换pH值取决于血红蛋白溶液中存在的特定离子种类。在pH范围内，结晶机理与pH有关，但最终形成的晶体结构与pH无关。本文介绍了两种新发现的通过低pH途径参与脱氧血红蛋白结晶的中间体。第一种是由一类我们称之为大纤维的粒子组成的。纤维和大纤维的光学衍射图具有相似的强度分布和层线间距，这表明大纤维和大纤维是由一个共同的结构单元组装而成的，我们将其称为Wishner-Love双股。第二种新结构是脱氧血红蛋白s的准晶形式，这种准晶是由分子的双链层构成的，其排列方式与晶体内部类似。准晶电子显微照片的光学衍射显示，纵向无序存在于双股之间。电子密度沿晶体轴向下的投影提供的图像与负染色副晶体的电子显微照片非常相似。由于无序而出现在副晶体中的图案可以通过双链层之间的移位完全模拟。
Crystallization of sickle cell hemoglobin proceeds by distinctive pathways which depend upon the pH and the ionic composition of the crystallizing milieu. The pathways differ in that after fibers form they associate into different intermediates which then crystallize. We term the pathways “high pH” and “low pH”. The value of the transition pH between the high pH and low pH pathways depends upon the specific ionic species present in the hemoglobin solution. Over the pH range studied the mechanism of crystallization is pH-dependent but the structure of the crystals ultimately formed is not.In this paper we describe two newly discovered intermediates involved in the crystallization of deoxyhemoglobin Sviathe low pH pathway. The first of these consists of a class of particles we call macrofibers. Optical diffraction patterns of fibers and macrofibers have similar intensity distributions and layer-line spacings suggesting that macrofibers and fibers are assembled from a common structural unit which we take to be the Wishner-Love double strand.The second new structure is a paracrystalline form of deoxyhemoglobin S. The paracrystal is built from layers of double strands of molecules in an arrangement similar to that within the crystals. Optical diffraction of electron micrographs of paracrystals reveals that longitudinal disorder is present between double strands. Projections of the electron density down thecaxis of the crystal provide images very similar to those in electron micrographs of negatively stained paracrystals. The patterns appearing in the paracrystal due to the disorder can be fully simulated by shifts between the layers of double strands.