analyses has been of primary importance for protein engineers, biochemists, and
pharmacologists.
On Earth, the crystallization process is hindered by forces of sedimentation and convection
since the molecules in the crystal solution are not of uniform size and weight. This leads to
many crystals of irregular shape and small size that are unusable. However, the microgravity
environment aboard the ISS is relatively free from the effects of sedimentation and convection
and provides an exceptional environment for crystal growth.
SPACE BENEFITS
The crystals grown in microgravity are able to grow larger and more organized than those
grown on Earth. The results from this investigation may further human space exploration
efforts by creating technological and biological advancements as a direct result from this
research.
RESULTS
Preliminary analysis indicated that at
least 65% of the macromolecules flown
in the CPCG-H experiments produced
diffraction-sized crystals. X-ray
diffraction studies of these crystals
were conducted, and the data were
used to determine and refine the 3-D
structures of these macromolecules.
Three benchmark proteins, ML-I,
Thermus flavus 5S RNA, and BARS,
were flown to validate the
performance of the hardware.
Diffraction-quality crystals, which were
obtained from all of these proteins,
yielded X-ray diffraction data
comparable to those previously collected on Earth-grown crystals. Since the structure of each
of the benchmark proteins is known to high resolution, these results indicate that the new
HDPCG assembly worked very well, successfully producing high-quality crystals of the
benchmark proteins.
Synchrotron diffraction data, collected from the space crystals of the BARS protein, were
comparable in resolution but more intense and showed significantly less mosaicity than data
from Earth-grown crystals. This indicates that the space-grown crystals had a higher order at
the molecular level, and the X-ray diffraction data from the space crystals produced a more
complete data set. These results contributed significantly to the structural study of BARS
(Nardini 2002).
ISS004E10827 – Astronaut, Carl Walz works with
CPCG-H in US Laboratory during International Space
Station Expedition 4.