Advancing Membrane Protein Crystallization By Using Microgravity (CASIS PCG HDPCG-2) - 11.22.16

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Advancing Membrane Protein Crystallization by Using Microgravity (CASIS PCG HDPCG-2) focuses on the crystallization of the cystic fibrosis (CF) protein and other closely related proteins. It aims to yield high-quality crystals, which could be used by researchers to determine protein structure and improve drugs currently used to treat cystic fibrosis, a life-threatening lung disease caused by a genetic mutation. Crystallizing proteins in microgravity is essential in the process of drug development because it allows scientists to grow larger and more ordered crystals for treating certain diseases in the absence of the effects of gravity.
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Information Pending

The following content was provided by Stephen Aller, Ph.D., and is maintained in a database by the ISS Program Science Office.
Experiment Details


Principal Investigator(s)
Stephen Aller, Ph.D., University of Alabama at Birmingham, Birmingham, AL, United States

Information Pending

Information Pending

Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)

Sponsoring Organization
National Laboratory (NL)

Research Benefits
Scientific Discovery

ISS Expedition Duration
March 2014 - September 2014

Expeditions Assigned

Previous Missions
HDPCG tray carrying the same sample blocks flew installed in a Commercial Refrigerator Incubator Module (CRIM) during Expeditions 2 and 4 and on STS-107.

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Experiment Description

Research Overview

  • The shapes of many medically relevant proteins are unknown, but would be extremely useful for accelerating the process of preparing new drugs to cure diseases. In this investigation, the cystic fibrosis protein, cystic fibrosis transmembrane conductance regulator (CFTR), and closely related proteins are crystallized to further drug development.
  • Researchers plan to grow crystals of medically relevant proteins to accurately determine their shape to fit new drugs. The proteins chosen are proving extremely difficult to crystalize on Earth and it is believed that zero-gravity will allow the crystals to grow. This investigation crystallizes CFTR using the unique microgravity environment to increase the crystal quality and size compared to protein crystals grown on Earth.
  • Clear visualization of a specific region on the CFTR would greatly accelerate the design of new drugs to cure the CF disease.

In microgravity, the elimination of sedimentation and convection produces a highly unique environment for space-based experiments such as protein crystallization. The human body contains over 100,000 proteins that play important roles in the everyday function of the body such as the formation of major components of muscle and skin, and how the body fights diseases. In order to fully understand the function of proteins, three-dimensional structural information becomes necessary. The structure of individual proteins can be studied with the growth of high quality crystals in which the molecules of the protein are arranged in a regular, repeating pattern. In order to produce high-quality crystals of a protein, it must be reasonably pure with respect to other contaminating proteins, it must be homogeneous and it's three-dimensional conformation relatively stable. Crystallization occurs in aqueous solution when purified protein molecules are coaxed to slowly self-associate, through relatively weak interactions such as ionic or hydrogen bonds. Individual protein molecules align themselves in a repeating series of "unit cells" by adopting a consistent orientation that eventually forms a crystal with sharp facets. Protein crystallization serves as the basis for X-ray crystallography, wherein a crystallized protein is used to determine the protein’s three-dimensional structure via x-ray diffraction. Crystallization is performed using the Vapor Diffusion technique inside the Handheld HDPCG. This technique is also known as the hanging drop method of crystal growth. This process entails a droplet containing purified protein, buffer, and precipitant being allowed to equilibrate with a larger reservoir containing similar buffers and precipitants in higher concentrations. Initially, the droplet of protein solution contains an insufficient concentration of precipitant for crystallization, but as water vaporizes from the drop and transfers to the reservoir, the precipitant concentration increases to a level optimal for crystallization.

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Space Applications
In general, crystals grown in microgravity grow larger and in a more perfect form than those grown on Earth, because the effects of gravity are removed. CASIS PCG HDPCG-2 uses the International Space Station as a research platform for scientific investigations that are difficult or impossible to attain on Earth. The investigation could lead to a valuable new field of space-based protein crystallography research, especially for medically relevant proteins whose size or structure make them difficult to create on Earth.

Earth Applications
Determining the shapes and structure of medically relevant proteins is crucial for developing new drugs that can interact with them, including drugs that could treat or cure diseases. The CASIS PCG HDPCG-2 investigation crystallizes the cystic fibrosis protein, cystic fibrosis transmembrane conductance regulator (CFTR), and other closely related proteins. Researchers previously crystallized the protein on Earth, and microgravity-based crystallization can offer an important comparison. Unraveling the structure of this protein could enable researchers to design drugs to treat cystic fibrosis, which would offer significant commercial value as well as an improvement in the quality of life for patients with CF.

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Operational Requirements and Protocols

  • Preflight late loading (~L-24 hours) and postflight early access (R+48) required
  • Temperature Controlled environment
    • Turnover-Launch <-20°C and +4 (+2/- 3°C)
    • On-Orbit +4°C (+2/- 3)
    • Return <-20°C
  • Minimal crew time: ~ 60 minutes
    • 30 minutes for access from cold stowage and sample activation (2 blocks)
    • 30 minutes at end of mission to deactivate (2 Blocks) and stow in Cold stowage for return.
  • Quiescent microgravity environment during the sample activated period.

  • Cold Stowage unpacking
  • Handheld HDPCG Activation
  • Handheld HDPCG Deactivation
  • Cold Stowage packing

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Decadal Survey Recommendations

Information Pending

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Results/More Information

Information Pending

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Related Websites

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Handheld HDPCG Design – Illustration depicts the Handheld HDPCG Assembly. A small metallic container that houses five Level III Sample blocks and a small Activation/Deactivation Tool. Imagery courtesy of CASIS.

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Handheld HDPCG Design – Illustration the individual sample Block (five per Handheld Assembly). Image courtesy of CASIS.

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Handheld-HDPCG Design – Vapor Diffusion Sample Blocks configuration from Launch to Landing

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Handheld-HDPCG – Crystal formation inside Sample Block. Image courtesy of CASIS.

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image NASA Image: ISS041E078028 - NASA astronaut Reid Wiseman retrieving Ambient Handheld High Density Protein Crystal Growth (HDPCG) Unit.
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image NASA Image: ISS041E078032 - NASA astronaut Reid Wiseman retrieving Ambient Handheld High Density Protein Crystal Growth (HDPCG) Unit.
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image NASA Image: ISS041E078040 - NASA astronaut Reid Wiseman retrieving Ambient Handheld High Density Protein Crystal Growth (HDPCG) Unit.
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