Abstract
This experiment was conducted using the microgravity environment in space to prepare single crystals of good crystallinity in which protein molecules are very well ordered. Five kinds of protein samples: hen egg-white lysozyme (2 different crystallization conditions), horse skeletal myoglobin, ω-Amino acid: pyruvate aminotransferase from Pseudomonas sp. F-126, and Rhizopus niveus lipase, were used for crystallization, which was carried out according to the batch method for 7days at 20°C. Among these protein samples, crystals were produced from the four samples and the particularly noteworthy results could be obtained from lysozyme at pH4.5 and ω-amino acid:pyruvate aminotransferase. In this space experiment, crystal growth proceeded at a slower rate than expected, compared with a control experiment on earth. Furthermore, it was proved that space-grown single crystals possessed a good crystallinity although they were not always of an optimal shape and size for X-ray crystallography. Depending on the protein samples and the crystallization conditions, crystal nuclei grew in different shapes of crystals from those of ground-grown ones due to the influence of the gravity field in space.
