A macromolecule is a polymer, especially one composed of more than 100 repeated monomers (which are single chemical units). This report focuses on biological macromolecules, such as proteins, proteins with DNA, and RNA.


A culture or growth medium contains nutrients and provides a favorable environment for the growth of cells or tissues.


When biotechnology experiments are performed on the space shuttle or the International Space Station, the gravitational force experienced by the cells or the protein crystals is not exactly zero, but it is much less than the gravitational force experienced on Earth. On the ISS, researchers expect to be able to conduct experiments for which the gravitational force is approximately one-millionth of what it is on Earth.

Microgravity Research Division:

The unit at NASA that contains research on the behavior of systems in the microgravity environment. Includes five disciplines: Biotechnology, Combustion Science, Fluid Physics and Transport Phenomena, Fundamental Physics, and Materials Science. The Biotechnology program contains the work on protein crystal growth and cell science discussed in this report.

Middeck Locker Equivalent:

Standard size of transport and experimental units on the space shuttle and the space station. Each MLE is 18.2″ wide by 10.7″ high by 20.4″ deep, and the modular equipment that fits in the MLE can weigh approximately 60-70 pounds. Eight MLEs fit in each EXPRESS rack.


A measure of the misalignment between small coherent blocks of individual molecules within a protein crystal. Lower mosaicity results in higher quality X-ray diffraction data.

NASA Research Announcement:

Solicitation and instructions for grant applications for NASA funding for ground and flight experiments. Released approximately every two years.


A measure of how much detail can be obtained from X-ray diffraction data used for structure determination of protein crystals. The resolution, typically measured in angstroms, is specifically the minimal Bragg spacing to which diffraction measurements can be obtained. The smaller the resolution is, the more details are revealed about the protein structure.

Rotating-Wall Perfused System:

Instrument that houses a rotating-wall vessel and associated support equipment for experiments on the ISS.

Rotating-Wall Vessel:

Designed for culturing cells in a low-shear, low-turbulence environment. On Earth, the rotating walls set up laminar flow in order to randomize the force vector felt by the cell or tissue cultures. In space, the rotation produces Couette flow to augment mass trasport. Also known as a bioreactor.

Space Products Development Office:

Responsible for NASA's commercial product development program to encourage and increase the United States' industry involvement and investment in space-based materials processing and biotechnology technologies. Oversees the Commercial Space Centers, such as the Center for Macromolecular Crystallography at the University of Alabama at Birmingham. Responsible for the XCF, which is in development at this center.


A facility that produces high energy X rays by accelerating electrons along a circular path. These X rays are used for diffraction studies of macromolecular crystals to gather data that can be employed to determine the macromolecule's structure.

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