Grant-in-Aid for international Scientific Research
|Allocation Type||Single-year Grants|
|Research Institution||Research Institute for Food Science|
AIBARA Shigeo. Research Institute for Food Science, Kyoto University, asscio. professor, 食糧科学研究所, 助教授 (20027197)
DELUCAS Lawr University of Alabama at Birmingham, Cent, 教授
BUGG Charles E. Center for Macromolecular Crystallography, University of Alabama at Birmingham, Cent, 教授
NAKAJIMA Masamitsu. Faculty of Technology. Kyoto University, 工学部, 助教授 (60025939)
DELICAS Lawrence J. Center for Macromolecular Crystallography, University of Alabama at Birmingham
LAWRENCE J D University of Alabama at Birmingham Cent, Professor
CHARLES E Bu University of Alabama at Birmingham Cent, Professor
|Project Period (FY)
1992 – 1993
Completed(Fiscal Year 1993)
|Budget Amount *help
¥8,200,000 (Direct Cost : ¥8,200,000)
Fiscal Year 1993 : ¥3,100,000 (Direct Cost : ¥3,100,000)
Fiscal Year 1992 : ¥5,100,000 (Direct Cost : ¥5,100,000)
|Keywords||Micrograviy / Protein / Lysozyme / Crystal growth / Space station / X-ray crystallographic analysis / Space shuttle / Vapor diffusion method|
This investigation was planned to carry out the objectives that protein single crystals of better quality are prepared by the vapor diffusion and batch methods using a microgravity environment in space and also the space-grown crystals are compared with the earth-grown ones.
The first year (1992) twice space-experiments were conducted by space shuttles (STS-42 and STS-47). Eight different kinds of protein samples were used for crystallization, and one (STS-42) and four(STS-47)kinds of them were obtained in single crystals. Especially, omega-amino acid : pyruvate aminotransferase and lysozyme (monoclinic crystals) were the single crystals of good diffraction quality.
The second year (1993), making lysozyme the keynote of crystallization, twice space-experiments were also conducted : once by using a space shuttle and another by the space station. We succeeded in preparing 7 different kinds of protein crystals from 4 proteins under the various crystallization conditions aboard the space sta
tion, while one kind of crystal from two proteins by using a space shuttle. We drew the following conclusions from the space crystallization experiments.
1. Crystal growth proceeded at a slower rate in the microgravity environment in space.
In a microgravity environment, neither difference in gravity between solute and protein molecules should exist, nor should convection in the solution occur. For this reason, both nucleation and crystal growth processes should proceed by diffusion alone.
2. It is suggested that the behavior of protein molecules must be different from that on the ground.
Taking into account that the shape of single crystals is dependent on the characteristics of the crystal nuclei, there is every likelihood in a space environment that different crystal nuclei appeared due to a little difference in the physical characteristics of the protein's molecular surface even under the same crystallization conditions. Therefore, protein single crystals differing the crystallographic properties (crystal shape, crystal lattice and crystallinity) would easily grow in the species of proteins and the crystallization conditions.
3. Single crystals of good diffraction quality with less mosaicity were obtained. In situations where the nucleation process is influenced primarily by the molecular surface characteristics of proteins, it can be concluded that the degree of molecular arrangement in the crystal becomes higher as the protein molecules associate exactly with each other comparing with the gravity field on earth. It is very important for understanding the dynamic structure of proteins to establish the time-resolved crystallographic analysis by Laue method, and thus space-grown crystals with less mosaicity become more necessary.
4. Space-grown crystals easily sustained damages by X-ray irradiation, but it did not influence to the protein structure.
Our most urgent task is to develop the crystallization apparatus that the crystal growth can be ceased during a space experiment and also the crystals are able to be transported under the stable conditions even on the ground. Less