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The Center for Macromolecular Crystallography (CMC) has been involved in fundamental studies of protein crystal growth (PCG) in microgravity and in our earth-based laboratories. A large group of co-investigators from academia and industry participated in these experiments by providing protein samples and by performing the x-ray crystallographic analysis. These studies have clearly demonstrated the usefulness of a microgravity environment for enhancing the quality and size of protein crystals. Review of the vapor diffusion (VDA) PCG results from nineteen space shuttle missions is given in this paper.

The development and production of a zinc‐interferon alpha‐2b crystalline suspension on STS‐52 has accelerated our ability to prepare novel high quality pharmaceutical preparations. Crystalline suspensions of protein therapeutics have applications in drug delivery, formulation, and manufacturing. These applications require crystalline suspensions of relatively small particles (

Macroscale crystallization of zinc interferon alfa‐2b was achieved on STS‐52 in October 1992 in the Protein Crystallization Facility. Conditions for crystallization were established by adapting a microscale vapor diffusion method to a macroscale temperature induction method. A series of earth based pilot experiments established conditions to reproducibly crystallize zinc interferon alfa‐2b in high yield and under cleanroom conditions. As a control for the STS‐52 mission, a ground experiment was run simultaneously and in the same configuration as the flight experiment. Greater than 95% of the available protein crystallized in both the ground and flight experiments. Using a battery of physical, biochemical and biological characterization assays, demonstrated that sample processing, polysulfone bottle confinement and the conditions used for crystallization did not have a negative effect on protein integrity. Redissolved crystals from the flight and ground experiments showed full biological activity in a cytopathic effect inhibition assay as compared to an interferon control standard. Morphometric analysis comparing the overall length and width of the derived crystals showed a 2.4 fold increase in the length and width of the space grown crystals as compared to earth grown crystals. Space grown crystals have remained a stable free flowing suspension for over 2 years. Based on these results, further experiments are envisioned to investigate macroscale crystallization of biologically active macromolecules in microgravity.