diffraction analysis have been of primary importance for protein engineers, biochemists, and
pharmacologists.
Fortunately, the microgravity environment aboard the International Space Statoin (ISS) is
relatively free from the effects of sedimentation and convection and provides an exceptional
environment for crystal growth. Crystals grown in microgravity could help scientists gain
detailed knowledge of the atomic, three-dimensional structure of many important protein
molecules used in pharmaceutical research for cancer treatments, stroke prevention, and other
diseases. The knowledge gained could be instrumental in the design and testing of new drugs.
Protein crystal growth experiments aid the
generation of computer models of carbohydrates,
nucleic acids and proteins, and further advance the
progress of biotechnology. Understanding these
results can lead to advances in manufacturing and
biological processes, both in medicine and
agriculture.
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
PCG-STES is a suite of 9 experiments with additional shared samples for associated
investigators. Samples were taken to and from station five times for crystallization during
Expeditions 2, 4, 5, and 6. The logistical considerations of spaceflight affected some of the
results, as flight delays compromised some samples, and a jarring drop of the hardware shortly
after return on 11A/STS-113 probably destroyed any larger crystals that had formed during that
set of runs. PCG-STES samples in DCAM were in orbit prior to the Space Shuttle Columbia
accident and then spent an unprecedented 981 days (November 2002 - August 2005) on ISS
before being returned on the next space shuttle flight.
PCG-STES-IDQC
The PCG-STES-IDQC operated on the ISS during Expedition 2. The experiment used 2 types of
protein samples, basic fibroblast growth factor (bFGF) and thaumatin, used to grow crystals and
was active for 22 days. The bFGF samples were originally supposed to be loaded into 45 PCAM
chambers. Due to regulations that are related to flight, the original formulation of chemicals
was declared ineligible for fight. After a new set a chemical formulations were created, 18
chambers were loaded with the samples. Of the 18 chambers 8 produced crystals. The largest
crystal was about 80 micrometers x 50 micrometers. The thaumatin samples were originally to
Image from Vahedi-Faridi, A. Acta
Crystallographica, Section D, Biological
Crystallography, 2003. Shows a Manganese
Superoxide dismutases crystal grown in
microgravity. The pink color is a result from the
oxidized manganese in the active site.