Protein Crystal Growth in Space

Abstract

Protein crystal growth in space and on earth is conceptually explained in terms of both ther­modynamics and kinetics, and the results of crystallization of hen egg-white lysozyme using space shuttles and the space station MIR are summarized. In a microgravity environment in space, single crystals which have a good molecular packing appear, although crystal growth proceeds at a slower rate than that on earth. However, they are not always of an optimal shape and size for X-ray diffraction experiments. It is speculated that crystal shape is influenced by the characteristics of the molecular surface of the protein in space than it is more greatly on earth. Furthermore, it was observed that hen egg-white lysozyme happened to grow in single crystals of two different kinds of space groups in the same crystallization apparatus. The reasons why these phenomena occurred in space are dis­cussed.