Characteristics of dislocations in protein crystals

蛋白质晶体位错的特征

基本信息

批准号：
18560648
负责人：
KOJIMA Kenichi
金额：
$ 2.4万
依托单位：
Yokohama City University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

项目摘要

The object of this research is to understand characteristics of dislocations in protein crystals. We have attacked the problems by means of two ways. One is to observe clear images of dislocations and to determine the Burgers vectors by synchrotron X-ray topography. The other is to estimate the elastic energy of dislocations and the mechanical strength by an ultrasonic pulse echo method and an indentation method.Crystal defects, especially dislocations, in hen egg-white lysozyme crystals that are a typical protein crystal that have - multiple polymorphisms, for example tetragonal, orthorhombic and monoclinic forms were investigated by means of synchrotron white and monoclinic-beam X-ray topography. The observed topographic images of dislocations were much clearer compared to those of any protein crystals that have been reported so far. It was demonstrated that millimeter-size crystals larger than extinction length for X-ray topographic reflections are required to obtain clear images, t … More hat is, direct images for protein crystals. In addition the weak beam technique was found to be useful for obtaining clear images. Straight, curved and loop-type dislocations were clearly resolved on the topographs. This shows that dislocations observed in common inorganic and organic with small molecules can also be introduced even in protein crystals. The shapes and distributions of dislocations strongly depended on the crystal polymorphisms. This suggests that the growth mechanisms in the different crystal forms studied could differ. Therefore, X -ray topography provides a useful tool for the characterization of protein crystal dislocations.We have succeeded the measurement of all components of elastic constants in hen egg-white lysozyme crystals using an ultrasonic pulse echo method. The measurements of the sound velocity were performed using (110) , (101) and (001) crystal surfaces. Consequently, all the six elastic constants of the dehydrated tetragonal HEW lysozyme crystals were determined to be C_<11>= C_<22>= 12.44 GPa, C_<12> =7.03 GPa, C_<13>= C_<28> =8.36 GPa, C_<88> =12.79 GPa, C_<44>=C_<55> =2.97 Gpa and C_<66>=2.63 Gpa, respectively.In addition, Mechanical properties of high quality tetragonal hen egg-white lysozyme single crystals, which are one of protein crystals were investigated by the indentation method. The indentation marks were clearly observed on the crystal surface and no elastic recovery of them occurred. The value of the micro-Vickers hardness in wet condition was estimated to be about 20 MPa at room temperature. The hardness greatly depended on the amount of water (intra-crystalline water) contained in the crystals. The hardness increased with increasing evaporation time to air at room temperature. It reached the maximum at about 260 MPa, which is 20 times as much as that in the wet condition. The origin of such a change in hardness was explained in terms of the dislocation mechanisms in lysozyme single crystals. Less

这项研究的目的是了解蛋白质晶体中位错的特征。我们通过两种方式攻击了问题。一种是观察脱位的清晰图像，并通过同步X射线地形确定汉堡向量。另一种是通过超声脉冲回声方法和凹痕方法估算错位的弹性能量和机械强度。在典型的典型蛋白质晶体中，晶体缺陷，尤其是脱位，是一种具有多种多态性的典型蛋白质晶体，例如，由四型多态形式进行了调查的形式。单斜梁X射线地形。与迄今为止据报道的任何蛋白质晶体相比，观察到的脱位的地形图像要清晰得多。已经证明，需要用于X射线地形反射的毫米大小大于延伸长度，以获得清晰的图像，t…更多的帽子是蛋白质晶体的直接图像。另外，发现弱梁技术可用于获得清晰的图像。在地形上清楚地解决了直，弯曲和环形型位错。这表明，即使在蛋白质晶体中也可以引入常见的无机和有机物中观察到的位错。位错的形状和分布在很大程度上取决于晶体多态性。这表明不同晶体形式的生长机制可能会有所不同。因此，X射线地形为蛋白质晶体位错方面的表征提供了有用的工具。我们使用超声波脉冲Echo方法成功地测量了母鸡鸡蛋白溶菌酶晶体中弹性常数的所有组件。使用（110），（101）和（001）晶体表面进行声速的测量值。因此，确定脱水四方HEW溶菌酶晶体的所有六个弹性常数为C_ <11> = C_ <11> = C_ <22> = 12.44 GPA，C_ <12> = 7.03 GPA，C_ <13> = C_ <13> = C_ <13> = C_ <28> = C_ <28> = 8.36 GPA，C_ <88> C_ = 12.79 gpa，C_ <88> = 2.2.79 gpa，c_ = 44 = 44 = 44> 2. GPA和C_ <66> = 2.63 GPA。在加法中，高质量的四方鸡蛋鸡蛋溶菌酶单晶的机械性能是通过压痕方法研究了蛋白质晶体之一。在晶体表面清楚地观察到了压痕标记，并且没有发生弹性恢复。在潮湿条件下，微磁力硬度的值估计在室温下约为20 MPa。硬度在很大程度上取决于晶体中包含的水量（晶体内水）。由于在室温下蒸发时间增加，硬度随着蒸发时间的增加而增加。它达到约260 MPa的最大值，在湿条件下的最大值是20倍。这种硬度变化的起源是用溶菌酶单晶的脱位机制来解释的。较少的