Abstract
For successful protein crystallization in microgravity environment, the following four points are essential: high-quality protein samples and well-optimized crystallization conditions with high reproducibility, crystallization conditions which are optimized for counter-diffusion method, and crystallization conditions which enhance microgravity effects. To meet these points, we have a strategy that we first evaluate the protein samples and crystallization conditions by charge-density calculation, SDS-PAGE, Native-PAGE, high-performance ion-exchange column chromatography, DLS and preliminary crystallization experiment by vapor-diffusion method. Then according to the results of these evaluation, we make a trial of improvement of the protein samples and crystallization conditions. If the results of the evaluation are consistent with the charge density, good protein crystals grow in most cases. For the crystals grown in JAXA PCG (protein crystal growth) space experiment, harvesting and cryocooling of the crystals from capillaries require some skills. In this review, we introduce these techniques for users who have already participated or will participate in JAXA PCG.
