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Fact sheet number: FS-2001-11-184-MSFC
Missions: Expedition Four, ISS Mission UF-1, STS-108 Space Shuttle Flight, return flight 8A, STS-110 Experiment Location on ISS: U.S. Lab EXPRESS Rack 4 Principal Investigators: Dr. Daniel Carter, New Century Pharmaceuticals, Inc., Huntsville, Ala.; Dr. Craig Kundrot, NASA's Marshall Space Flight Center in Huntsville, Ala.; Dr. Aniruddha Achari, NASA's Marshall Space Flight Center in Huntsville, Ala. Project Manager: Todd Holloway at NASA's Marshall Space Flight Center in Huntsville, Ala. Overview Structural biological experiments conducted in the Single-locker Thermal Enclosure System (STES) may provide a basis for understanding the function of important macromolecules and possibly contribute to the development of new macromolecules. The scope of biological macromolecules includes proteins, polysaccharides and other carbohydrates, lipids and nucleic acids of biological origin, or those expressed in plant, animal, fungal or bacteria systems. The fundamental goal for growing biological macromolecular crystals is to determine their structure and the biological processes in which they are involved. Scientists select macromolecules, crystallize them, and analyze the atomic details -- often by using X-ray crystallography. By sending an intense X-ray beam through a crystal, scientists try to determine the 3-dimensional atomic structure of the macromolecule. Understanding these structures may impact the studies of medicine, agriculture, the environment and other biosciences. Every chemical reaction essential to life depends on the function of these compounds. Microgravity - the near weightlessness condition created inside a spacecraft as it orbits the Earth - offers an environment which sometimes allows the growth of macromolecular structures - crystals -- that show greater detail when exposed to X-ray diffraction (the pattern showing the structure of crystals when exposed to X-ray beams) than those crystals grown on Earth. The International Space Station provides for longer-duration experiments in a more research-friendly, acceleration-free (no change in the rate of speed, or velocity, of the spacecraft that could affect the experiments), dedicated laboratory, than provided by the Space Shuttle. Mission UF-1 is a continuation of similar structural biology experiments to characterize the use of the Space Station for this type of research. Experiment Operations The Single-locker Thermal Enclosure System for the structural biology experiment is an incubator/refrigerator module that can house different devices for growing biological crystals in microgravity. On the Shuttle STS-108 mission to the International Space Station, scheduled for launch in December 2001, two STES units will be flown - each housing a Protein Crystallization Apparatus for Microgravity (PCAM). Once on board the International Space Station, the units will be located in the U.S. Lab EXPRESS Rack 4. The experiments are scheduled to return to Earth aboard the Shuttle STS-110 Mission in March 2002. Each Protein Crystallization Apparatus for Microgravity (PCAM) is designed to grow crystals using the "sitting drop" method of vapor diffusion. These crystals are grown inside each of the six PCAM cylinders. Each cylinder is 15.2 inches (38.61 centimeters) long and 3.2 inches (8.128 centimeters) in diameter. In each cylinder, there are nine plastic growth trays. Each tray has seven sample wells, or chambers, covered by a synthetic rubber seal. The six PCAM cylinders house a total of 378 biological crystal experiments. A total of 756 biological crystal experiments will be housed in both STES PCAM units. Samples are prepared on Earth by placing a drop of the biological sample solution and precipitant solution together in the sample well. The sample well is surrounded by a donut-shaped reservoir that holds absorbent material similar to that of a disposable diaper. The material in the reservoir is used to absorb the evaporating component as crystallization occurs. A synthetic rubber seal placed on the tray isolates the sample drop from the reservoir -- until the start of the experiment in microgravity -- and keeps the crystals from forming on Earth or bouncing out of their sample chambers. Once the experiments are taken aboard the Space Station, a crewmember will open the front of the STES units and rotate a shaft on the end of each cylinder with a socket wrench. This loosens the seals and allows evaporation to begin. Once all 12 cylinders are activated, the STES units are closed and the samples are left to crystallize. Near the end of the mission, the procedure is reversed to deactivate the experiments and reseal the chambers for the return to Earth. STET PCAM Flight History (Mission/Year) STS-62: 1994 Crew Operations Aside from experiment activation and deactivation, crew interaction aboard the Space Station for the PCAM apparatus is limited to 10-minute checks three times a week during the mission. Benefits With science being performed on the International Space Station, scientists are no longer restricted to relatively short-duration flights to conduct structural biology experiments. This research will enable the more accurate mapping of the 3-dimensional structure of macromolecules. Once the structure of a particular macromolecule is known, it may become much easier to determine how these compounds function. Every chemical reaction essential to life depends on the function of these compounds. More Information Additional information on structural biology crystal growth in microgravity is available at: http://www.scipoc.msfc.nasa.gov/ A photo of a PCAM experiment tray is available at: http://www.ssl.msfc.nasa.gov/msl1/images/pcambig.jpg
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