Studies on structure analysis of space-grown protein crystals - Relationship between structure and molecular functions -

利用航天飞机在空间微重力环境下进行了鸡蛋清溶菌酶的气相扩散结晶实验，从结构生物学角度考虑了微重力对蛋白质晶体生长的影响。利用气相扩散法原理研制的结晶装置，在地面和空间环境中分别结晶了单斜、正交（20℃和37℃）和四斜（pH0.7和pH0.1）3种不同晶系的4种单晶，并对它们的晶体学数据进行了比较。在两种不同形状的单斜晶体中，一种是矩形形式，另一种是极薄的腭状形式。他们很容易通过外表彼此区分开来。在太空实验中，后者晶体出现的可能性很大。然而，分子 关于我们 从X射线晶体学分析的结果可以看出，这些晶体中的r填充，尽管这些晶体的晶格略有不同。因此，认为形态的差异是由晶面的生长速度的差异引起的。对于斜方晶系晶体，空间生长晶体的分子堆积与地面生长的四斜晶系或单斜晶系晶体在30℃以上的高温条件下转变的分子堆积有很大的不同。（空间和地球生长晶体的单斜、斜方和四方晶形式），它们的分子结构进行了比较。空间和地面生长的晶体分子结构之间没有显着差异，但它们有一些相对波动的区域在分子表面。在蛋白质结合水结构方面，溶菌酶铰链区通常有三个高度保守的水分子。这些事实表明，蛋白质结构本身不受微重力的影响，但蛋白质分子在成核过程中的相互作用受到了显著影响。在空间上，假设蛋白质分子的表面特征e。G.在空间微重力场作用下，形成了晶核形成的分布，形成了衍射质量较好（镶嵌性较低）的单晶。少

Crystallization experiment of hen egg-white lysozyme according to the vapor diffusion method was carried out by using the space shuttle under the microgravity environment in space, and the influences of microgravity on the protein crysta growth was considered from the aspect of the structure biology. The crystallization apparatuses produced according to the principle of the vapor diffusion method were used.Four kinds of single crystals containing 3 different crystal systems (monoclinic, orthorhombic (20℃ and 37℃) and tetragonal (pH0.7 and pH0.1) crystals) were crystallized on the ground and in space environments, and the crystallographic data of them were compared with each other. Of the two different shapes of monoclinic crystals, one is a rectangular form and the other is an extremely thin palate-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. However, the molecula … More r packing in the crystal from the results of X-ray crystallographic analysis although the crystal lattice of these crystals were slightly different. The difference in the morphology is, therefore, considered to be derived from difference in the growth rate of the crystal plane. Regarding orthorhombic crystals, 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℃ from the ground -grown tetragonal or monoclinic crystals.After X-ray crystallographic analyses of seven crystals from the three different space groups (monoclinic, orthorhombic and tetragonal forms of the space- and earth-grown crystals), their molecular structure were compared. Significant differences among the molecular structures were not found between the space- and ground-grown crystals although they had some relatively fluctuating regions in the molecular surface. Regarding the water structure bound to the protein, three highly or dared 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 in the formation of crystal nuclei, and the single crystals of better diffraction quality, (less mosaicity) were consequently formed under the micro gravity field in space. Less