LONG DURATION GROWTH OF PROTEIN CRYSTALS IN MICROGRAVITY ABOARD THE MIR SPACE STATION

A series of protein crystallization experiments using hen egg white lysozyme and D-amino transferase were flown on the Soviet space station MIR from December, 1989, to February, 1990. The The total duration of the crystal growth phase of the experiment was 56 days. These experiments were designed to evaluate MIR as a platform for protein crystallization; the temperature, radiation, and other environmental parameters of the space station were found to be satisfactory for such experiments. The size and diffraction characteristics of the crystals grown in microgravity are superior to crystals grown on earth using identical methods and hardware. In a second independent comparison with crystals grown on earth by standard laboratory techniques, the observed improvement in the size, lattice order, and diffraction quality of microgravity crystals is small, but measurable, for these two specific proteins. In addition, crystals grown in microgravity sometimes exhibit different crystal morphologies compared to crystals grown on earth under identical conditions. This effect provides a second reason to consider microgravity as a variable in protein crystal growth.