Overview of China's space life science and biotechnology achievements

(1) Results of protein crystallization study on Shenzhou II/III spacecraft

a) For the first time, in-depth structural comparison of space and ground crystals was conducted, and correct results were obtained.

The quality analysis and comparison of space and ground crystals is an important part of this research. Among them, the most important research is to compare the structure of space and ground crystals. By comparing and analyzing the structure of two protein crystals grown on a Chinese satellite in 1994, it is found for the first time that the electron density map calculated by space protein crystals contains more structural details. It was subsequently confirmed by research in cooperation with foreign counterparts. This not only specifically proves that the protein crystals grown in space are of higher quality than those grown on the ground, but also shows that the protein crystals grown in microgravity have an improved water-binding structure. The structural studies of these two protein crystals also suggest that the improvement of the binding water structure in the protein crystals with high solvent content is more obvious. This difference may provide rational principles for the selection of space protein crystal samples.

b) A systematic numerical study of liquid-liquid diffusion crystallization was carried out for the first time using the results of space experiments.

The difference of solute transport in solution is the main reason for the effect of gravity on crystal growth. Liquid-liquid diffusion crystallization method is also a promising crystallization method for spatial growth of protein crystals. The first systematic numerical study of liquid-liquid diffusion crystallization was carried out in response to the unsuccessful attempt on the Space shuttle in 1995 with an American device. Through numerical simulation of solute diffusion before nucleation, some rules which determine the success rate of this crystallization method are obtained. This explains the failure to get good results on the space shuttle with the American device and has been confirmed by gel crystallization experiments. The model protein crystallization experiments conducted on Shenzhou 3 spacecraft further confirmed that these rules exist under microgravity conditions, and also clearly demonstrated the advantages and disadvantages of gel crystallization. These studies have laid a foundation for developing related techniques and designing space protein crystallization experiments with high success rate. Numerical simulation of solute diffusion after nucleation by liquid-liquid diffusion crystallization showed for the first time the solute poor layer around growing crystals, which is very important to explain microgravity improvement of protein crystallization.

c) Significant progress has been made in the study of crystal structure of related proteins.

Human epidermal growth factor, which is very important for cell growth and reproduction, has been intensively studied. Through the continuous exploration of crystallization methods and conditions, high quality crystals were grown for the first time, and then the crystal structure of the protein was determined for the first time. The results were published in the JBC international journal with high influence factor. This structure shows that its remarkable conformational flexibility is the main reason for the difficulty in growing crystals, and it may be a candidate for studying the effect of microgravity on protein crystallization. A total of 16 proteins from nearly 10 research institutions at home and abroad participated in the space protein crystallization experiment. These proteins perform a variety of biological functions, and their research has important theoretical significance or drug design prospects. The crystallization rate is over 70%, and five kinds of protein crystals with good quality are obtained, and the success rate reaches the international advanced level; Through the quality inspection of protein crystals, it is found that at least three protein crystals have diffraction power exceeding the published data.