Protein crystallization and development of the apparatus

利用航天飞机在空间微重力环境下进行了蛋清溶菌酶的结晶实验。根据气相扩散法的原理使用了晶化装置，在生长单斜晶系的晶化条件下，得到了2种不同形态的晶体。在相同的晶化条件下，还出现了正交晶型晶体。另一方面，除了四方晶体外，在生长四方晶体的结晶条件下，也生长出了看似为正交晶的晶体。在两种不同形状的单斜晶体中，一种是矩形晶体，另一种是极薄的板状晶体。他们很容易从外表上区分开来。在太空实验中，出现后一种晶体的可能性很大。由于这两个单环…晶体中的分子堆积然而，更多的NiC溶菌酶被发现是相同的排列。从X射线晶体分析的结果来看，空间生长的晶体和地面生长的晶体的形态差异被认为是由于晶面生长速度的不同造成的。对于斜方晶体，空间生长晶体的分子堆积与研磨生长的四方晶体或单斜晶体在高于30ﾟC的温度条件下转变的高温形式有很大的不同。据报道，出现了具有相同分子排列的正交晶体，但晶体的分辨率限制在6*，此后没有发表更多的报道。其次，空间生长的四方晶体与研磨生长的晶体具有相同的分子堆积和相同的形貌，结果表明，在空间微重力环境下，即使在相同的结晶条件下，也会出现不同空间群的晶体。对三种不同空间群(单斜晶系、正交晶系和四方晶系)的六种晶体进行了X射线晶体分析，比较了它们的分子结构。所获得的分子结构在空间生长的晶体和地面生长的晶体之间没有发现显着的差异，尽管它们在分子中有一些相对断裂的区域。关于与蛋白质结合的水结构，溶菌酶的铰链区通常保守三个高度有序的水分子。这些事实表明，蛋白质结构本身并没有受到微重力的影响，但成核过程中蛋白质分子之间的相互作用受到了显着的影响。在空间上，假设蛋白质分子的表面特征，如变化的分布和蛋白质分子表面的疏水区域控制着晶核形成过程中的分子间相互作用。较少

Crystallization experiement of hen egg-white lysozyme was conducted by using the space shuttle under the microgravity environment in space. The crystallization apparatuses were used according to the principle of the vapor diffusion method.In the crystallization conditions for growing monoclinic crystals, 2 morphologically different kinds of crystals were obtained. Furthermore, orthorhombic crystal appeared under the same crystallization conditions. On the other hand, crystals which seemed to be the orthorhombic crystal were also grown under the crystallization conditions for growing tetragonal crystals in addition to the tetragonal crystal. Of the two different shapes of monoclinic crystals, one is a rectangular form and the other is an extremely thin plate-like form. They are easily distinguished from each other by their appearances. In the space experiments, there was a strong likelihood of the latter crystals appearing. Since the molecular packing in the crystal of these two monocli … More nic lysozymes, however, revealed to be the same arrangement from the results of X-ray crystallographic analysis, the difference in the morphology between the space- and ground-grown crystals is considered to be derived from difference in the growth rate of the crystal plane. Regarding orthorhombic crystals, in contrast, the molecular packing of the space-grown crystals were quite different from that of the high temperature forms which are transformed under the temperature conditions higher than 30ﾟC from the ground-grown tetragonal or monoclinic crystals. It has been reported that the orthorhombic crystals possessing the same molecular arrangement appearred, but the resolution of the crystals is limited to 6* and no more report has been published thereafter. Next, the space-grown tetragonal crystals had the same molecular packing in the crystals as well as the same morphology as the ground-grown crystals.As the results, it turned out that crystals of the different space group happened to appear even under the same crystallization conditions in a microgravity environment in space. After X-ray crystallographic analyzes of six crystals from the three different space groups (monoclinic, orthorhombic and tetragonal forms of the space- and earth-grown crystals), their molecular structures were compared. Significant differences among the obtained molecular structures were not found between the space- and ground-grown crystals although they had some relatively fractuated regions in the molecule. Regarding the water structure bound to the protein, three highly ordered water molecules were commonly conserved in the hinge region of lysozyme. These facts suggest that the protein structure itself was not influenced by the microgravity but that the interaction of the protein molecules in the nucleation process was significantly affected. In space, it is assumed that the surface characteristics of the protein molecule e.g.the distributions of the change and the hydrophobic region on the surface of the protein molecule control the intermolecular interactions in the formation of crystal neuclei. Less