PROTEIN CRYSTALLIZATION DIAGNOSTICS FACILITY - INFLUENCE OF MASS TRANSPORT AND
SURFACE GROWTH PROCESSES ON PROTEIN CRYSTAL PERFECTION (PCDF)
Research Area: Macromolecular Crystal Growth
Expedition(s): 18- 20
Principal Investigator(s): ● Fermin Otalora Munoz, University of Granada, Granada, Spain
RESEARCH OBJECTIVES
The specific overall goal of the Protein Crystallization
Diagnostics Facility (PCDF) project is to investigate mass-
transport phenomena that control crystal quality: super
saturation level and fluctuation, impurity incorporation and
nucleation in homogeneous fluids. Such phenomena are
strongly affected by buoyancy being accompanied by
concentration and, consequently, density gradients that
indeed promote buoyancy driven convective instabilities.
EARTH BENEFITS
Without the convection and sedimentation effects induced by
Earth's gravity, the experiments carried out in the PCDF will
help to understand the fundamental processes that occur
during crystallization. Understanding the process of protein
crystallization can help to obtain better quality crystals. This in
turn will help improve their function in various applications,
such as in protein-based medicines where they are a means of
controlling the release rate of an active compound, or of increasing shelf-life.
SPACE BENEFITS
Zero gravity on the International Space Station helps to prevent the occurrence of negative
sedimentation impacts known from ground experiments and supports undisturbed crystal
formation. Precise knowledge of the nucleation process is crucial to grow sufficiently
homogeneous and large crystals, which may provide information on the protein molecule. The
results from this investigation may further human space exploration efforts by creating
technological and biological advancements as a direct result of this research.
RESULTS
The corrected and reprocessed Dynamic Light Scattering data obtained in the experiment
indicated the presence of 3 main particle populations during the experiment: the glucose
isomerase tetramer at approximately 6 nm, particles with an apparent radius around 200 nm,
and a third population with apparent size between 2 and 30 μm. For each of these, the
apparent size of the particle changed with reactor temperature during the nucleation
experiment. The reactor also contained glucose isomerase precipitate, complicating the
analysis. Nevertheless, the 200 nm particles seemed to fit well with the hypothesis of
metastable dense liquid clusters in pre-nucleation conditions.
Front view of Crystallization
Diagnostics Facility hardware. ESA
image.