JAPAN AEROSPACE EXPLORATION AGENCY PROTEIN CRYSTAL GROWTH (JAXA PCG), 114
INVESTIGATIONS
Research Area: Macromolecular Crystal Growth
Expedition(s): 19-ongoing
Principle Investigator(s): ● Kazunori Ohta, Japan Aerospace Exploration Agency, Tsukuba,
Japan
RESEARCH OBJECTIVES
The Japan Aerospace Exploration Agency Protein Crystal Growth (JAXA PCG) studies the growth
crystals of biological macromolecules using the counter-diffusion technique. JAXA PCG creates
high-quality protein crystals in a microgravity environment to apply to structural biology and
pharmaceutical activities.
EARTH BENEFITS
This investigation may contribute to society by creating
new drugs for diseases and new catalysts for the
environment or for energy production.
SPACE BENEFITS
This investigation is applied to new knowledge and not
specifically to advances in space exploration.
RESULTS
The JAXA PCG studies have been
performed for more than 20 years. JAXA has conducted protein
crystallization experiments aboard the International Space Station (ISS)
since 2003. In this experiment, over 300 protein samples were launched in
order to obtain high-quality crystals in space. In the past PCG missions, 60-
70% of the proteins experimented were crystallized as single crystals.
Excellent diffraction data used to determine the precise structure of
proteins were obtained for several different proteins.^ Detailed structural
analysis of those proteins are currently being conducted.In microgravity, the incorporation of molecules into the crystal highly
depends on diffusion. The incorporated molecules may be allocated in
order and the incorporation of impurity may be suppressed. Consequently,
these nature of microgravity environment brings the growth of the highly
ordered crystals. It is assumed that the formation of a protein depletion
zone (PDZ) and an impurity depletion zone (IDZ) around growing crystals under a microgravity
environment is due to the suppression of a convection flow. The combination of the crystal size
(R), the diffusion coefficiency of the protein molecule (D), and the kinetic coefficiency for the
protein molecule (β), Rβ/D, could be an index of the extent of these depletion zones. Larger
‘Rβ/D’ are favorable to maximize the effect of microgravity environment. 'D' can be decreased
ISS028E49720 – ISS crewmembers
Satoshi Furakawa (L) and Sergei Volkov
(R) holding the JAXA PCG during ISS
Expedition 28.Crystal photo of
alpha-amylase
(upper:grown on
ground, lower:
grown in space).
JAXA image