RECENT ACTIVITIES OF SPACE PROTEIN CRYSTALLIZATION IN CHINA. Ru-Chang Bi, Institute of Biophysics, Academia Sinica, Beijing 100101, P.R.China

Based on encouraging results obtained on the first mission in 1992, the second Chinese mission of protein crystallization was conducted in 1994 using tube-like vapor diffusion apparatus on a Chinese re-entry satellite. More than 14 different proteins have been tested on the two missions. In comparison with the first mission, much better results were acquired on the second mission. Besides hen egg-white lysozyme, an acidic phospholipase A2 from snake venom and hemoglobin from bareheaded goose have produced good- quality crystals. The positive effects of microgravity on protein crystal growth and even results of protein crystallization in space can be reproducible. As an important factor affecting protein crystal growth, the microgravity may display its role in different degree depending on the protein crystallized and the crystallization conditions used.

Our first attempt to grow protein crystals with the liquid-liquid diffusion method was carried out on the August 1995 flight of the US space shuttle, STS-69. The hardware, MDA Minilab developed by the Instrumentation Technology Associates in US, was employed in this space experiment. Although the experiment was restrained by some conditions, the three proteins which we supplied to use six diffusion cells in a MDA unit, were crystallized on this mission. An important finding of our experiments is that in contrast with the case of vapor diffusion technique, the optimized conditions for growing good protein crystals on Earth may be different remarkably from those to be optimized in space. These differences could be caused by the density-driven convection and will be discussed in this report.