Sam McKenzie checks the SNS accumulator ring.
Full size image available here
Biologists can image proteins using electron and atomic force microscopes. They can visualize the three-dimensional structure of proteins--amino-acid sequences folded in complicated ways--by using X rays at ORNL and other DOE labs. They also can identify proteins using mass spectrometers and predict their structure using supercomputers.
What they cannot "see" with these tools are a protein's most active and abundant components, their interactions, and their locations in protein complexes. These components are hydrogen atoms, and they can be seen only with neutrons. In two years Oak Ridge will offer biologists two powerful sources of neutrons.
The sources are the High Flux Isotope Reactor, which is already the best steady source of slow neutrons, and the accelerator-based Spallation Neutron Source, which will be the world's best source of pulsed fast neutrons, starting in 2006.
"HFIR and SNS will both have small-angle neutron scattering instruments, which will enable biologists to understand the structures and activities of proteins, lipids, and sugars," says Dean Myles, director of DOE's Center for Structural Molecular Biology (CSMB) at ORNL. "The SNS will also likely have a protein crystallography instrument and a reflectometer for better understanding cell-to-cell communication."
Because CSMB is offering all these tools to scientific users, Oak Ridge may someday become a neutron-rich mecca for biologists.
The Department of Energy's Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time.