Microgravity Growth of Single Antibody Crystals for Structure Determination (Microgravity Growth of Antibody Crystals in the Hand Held High Density Protein Crystal Growth ) - 08.05.14
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Microgravity Growth of Antibody Crystals in the Hand Held High Density Protein Crystal Growth Hardware (HDPCG) focuses on the crystallization of a human monoclonal antibody, a specialized type of protein made by immune cells that can bind to target cells or other proteins to perform a specific task, developed by the pharmaceutical company Merck Research Laboratories. The monoclonal antibody in this investigation is undergoing clinical trials for treatment of an immunological disease, and crystallizing it may help the pharmaceutical industry determine its physical structure, which could lead to new drugs. Protein crystals grown in microgravity can reach much larger sizes and more perfect structures than those grown on Earth, where gravity interferes with their formation.
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OpNom Merck PCG
Center for the Advancement of Science in Space (CASIS), Rockledge, FL, United States
Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)
National Laboratory (NL)
Earth Benefits, Scientific Discovery
ISS Expedition Duration
March 2014 - September 2014
Previous ISS Missions
Numerous protein crystal growth investigations have been completed on ISS. The HDPCG Principal Investigator (PI) has been the PI on 12 previous Space Shuttle flights and one ISS flight. These experiments were designed to explore microgravity effects on multiple pharmaceutical applications primarily using alpha interferon (Intron A™). These applications included structure determination, drug delivery and the purification of protein therapeutics. Space grown crystalline suspensions of alpha interferon from STS-70, because of their high quality and uniformity compared to earth grown crystals, were used in multiple primate pharmacological studies.
- Information gained by the growth of single monoclonal antibody crystals on the ISS suitable for structure will aid in the design of more effective and safe medicines in the future.
- To date, earth grown crystals of monoclonal antibodies are not of high enough quality for structure. With the absence of gravity and convection on the International Space Station, larger crystals with purer compositions and structures can be grown.
The disease causing protein and the drug that suppresses it can be compared to the relation between a "keyhole" and a "key." If the shape of the keyhole is discovered by examining the structure of the protein, treatment-oriented medicine with fewer side effects -- the key to fit the keyhole -- can be designed.
Growth of crystals that diffract to higher resolution could be the difference between getting interpretable and un-interpretable data, leading to a high resolution structure. Structural information could help in the understanding of the functional parts of monoclonal antibodies such as epitope binding and help envision the design of new and improved monoclonal antibodies.
An experiment comparable to the successful vapor diffusion conditions used on earth to generate crystals of size and quality for structure determination is designed using the Hand-Held High Density Protein Crystal Growth (HDPCG) hardware. Current earth grown crystals diffract to 3.5 Å; researchers anticipate, based on previous space shuttle experimental results, improvements in the proposed microgravity experiment to 2.5-3.0 Å.
The project uses very few resources and has a flexible strategy that makes it an ideal system for ISS. The HDPCG hardware launches passively in an ambient soft stowage bag and transfers to ISS ambient stowage. The experiment is activated by turning the sample cells 90 degrees clockwise to introduce the sample insert to the precipitant reservoir. Following approximately 11 days of crystal growth, the sample cells are turned 180 degrees clockwise to turn the protein insert opposite of the precipitant reservoir. The Hand-Held HDPCG hardware returns passively in an ambient soft stowage bag.
It is difficult to crystallize large proteins on Earth because gravity affects how they can grow. The Microgravity Growth of Antibody Crystals in the Hand Held High Density Protein Crystal Growth investigation depends on the International Space Station’s microgravity environment to crystallize a human monoclonal antibody. The investigation also builds on previous results from earlier flight experiments, and embodies the future use of the ISS as a scientific research platform.
The monoclonal antibody used in this investigation is currently being studied in clinical trials to treat an immunological disease. Protein crystallography can help scientists determine the structure of this protein. Understanding this structure could provide insight for developing new drugs, some of which could be delivered with an injection, rather than an intravenous catheter. It also aims to help scientists develop proteins that do not break down as quickly in the body, providing longer-acting or high-dosage medicines, benefitting many people on Earth.
- Time between turnover and launch: L-24 hours
- Ambient stowage
- Sample activation must be completed within six days following launch
- Sample deactivation can occur as soon as 11 days after activation
- Temperature cannot fall below 10°C
- Early recovery at the dock required, samples are shipped to laboratory for X-ray crystallography
Two Hand-Held HDPCG hardware units are transferred from ambient stowage on the ascent vehicle to ISS. To activate the experiment, an activation tool (which is attached to the side of the Hand-Held HDPCG hardware using Velcro) is removed and attached to each cell block (5 total per HDPCG unit). The cell block is turned 90° clockwise to align the sample insert with the precipitant solution. Crystals grow for approximately 11 days and the experiment is deactivated by attaching the activation tool to each cell block and turning 180° clockwise to turn the protein insert opposite of the precipitant reservoir. Prior to undock, the two Hand-Held HDPCG units are transferred to ambient stowage on the descent vehicle for return.