New Crystallization Systems Envisioned for Microgravity Studies

Laboratory-based systems have been constructed to demonstrate two methods which will allow for dynamic control of protein-crystal growth. The technologies developed in these systems will be incorporated into future flight hardware for use in microgravity studies. The first method uses a precisely controlled vapor-diffusion approach to monitor and control protein crystal growth. This approach utilizes a humidity sensor and various interfaces under computer control to effect virtually any evaporation rate from up to 40 different growth solutions simultaneously. A static laser-light-scattering sensor can be used to detect aggregation events and trigger a change in the evaporation rate for a growth solution. The second method exploits the varying solubility of proteins versus temperature to control the growth of protein crystals. This approach utilizes miniature thermoelectric devices under microcomputer control which change temperature as needed to grow crystals of a given protein. Complex temperature ramps are possible using this approach. A static laser-light-scattering probe is also included in this system as a noninvasive probe for detection of aggregation events. The systems constructed demonstrate significant advances in the ability of researchers to gain control of the protein-crystal growth process and will provide tremendous opportunities for microgravity research.