Bound-solvent structures for microgravity-, ground control-, gel- and microbatch-grown hen egg-white lysozyme crystals at 1.8 angstrom resolution

A number of methods can be used to improve the stability of the protein cry stal-growth environment, including growth in microgravity without an air-li quid phase boundary, growth in gels and growth under oil ('microbatch'). In this study, X-ray data has been collected from and structures refined for crystals of hen egg-white lysozyme (HEWL) grown using four different method s, liquid-liquid dialysis on Earth and in microgravity using the European S pace Agency's (ESA) Advanced Protein Crystallization Facility (APCF) on boa rd the NASA Space Shuttle Life and Microgravity Spacelab (LMS) mission (STS -78), crystallization in agarose gel using a tube liquid-gel diffusion meth od and crystallization in microbatch under oil. A comparison of the overall quality of the X-ray data, the protein structures and especially the bound -water structures has been carried out at 1.8 Angstrom. The lysozyme protei n structures corresponding to these four different crystallization methods remain similar. A small improvement in the bound-solvent structure is seen in lysozyme crystals grown in microgravity by liquid-liquid dialysis, which has a more stable fluid physics state in microgravity, and is consistent w ith a better formed protein crystal in microgravity.