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College Park, Maryland      June 6 - 10 , 2004

T2-A1 (1:30 PM): The PCS Neutron Protein Crystallography Facility at Los Alamos (Invited)

P. Langan, B.P. Schoenborn (Los Alamos National Laboratory)

The PCS (Protein Crystallography Station) at Los Alamos Neutron Science Center, is a high performance neutron protein crystallography beam line funded by the Office of Biological and Environmental Research of the U.S. Department of Energy. Beam-time is free to expert and non-expert users and is allocated twice a year through a call for proposals and a peer review process.

Although most protein structures are determined using x-rays, the position of hydrogen atoms and the coordination, sometimes even the position of water molecules, cannot be directly determined at resolutions typical for most protein crystals. Hydrogen atoms are the primary motive force in most enzymatic processes. Neutron diffraction is a powerful technique for locating hydrogen atoms even at resolutions of 2 to 2.5 and can therefore provide unique information about enzyme mechanism, protein hydrogen and hydrogen bonding.

For an experiment on the PCS, protein crystals have to be ~ 1 mm3 in volume. Crystals of perdueterated protein can be significantly smaller. Users of the PCS have access to neutron beam-time, perdeuteration facilities and also support for data reduction and structure analysis. The beam-line exploits the pulsed nature of spallation neutrons and a large electronic detector in order collect wavelength resolved Laue patterns using all available neutrons in the wavelength range 1 to 5 . This talk shall be used to describe the facility, some groundbreaking results from our second year of operation, and provides information about obtaining beam-time. Future technological developments that will greatly improve the performance of the PCS facility will also be discussed, as well as prospects for neutron protein crystallography at the SNS.

For more information about the PCS and experimental requirements, contact Paul Langan (505) 665 8125, langan_paul@lanl.gov or Benno P. Schoenborn (505) 665 2033, schoenborn@lanl.gov. The PCS is funded by the Office of Science and the Office of Biological and Environmental Research of the U.S. Department of Energy.

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