Courtesy of Lyncean Technologies
Advanced synchrotron radiation sources have revolutionized structural biology, allowing X-ray crystallographers to solve complex macromolecular structures. But as few of these soccer field-sized facilities exist worldwide, researchers have only limited access to them. Now researcher Ronald Ruth at the Stanford University Linear Accelerator Center has designed and is currently building a new desktop-sized synchrotron source called the Compact Light Source (CLS) that could permit universities and corporations to set up their own structural biology facilities. "Assuming it takes off, it is really going to change the way people are doing their X-ray crystallography research at home," says Bill Weis, professor of structural biology, Stanford University School of Medicine.
Conventional synchrotrons use large magnetic rings (roughly 305 m in diameter) to store high-energy electron beams. Undulating magnetic fields bend or "wiggle" the beams to produce X-ray radiation whose wavelength is proportional to the period of the magnets and the energy of the electron beam. A 5-GeV beam combined with a 2-cm undulator can produce 1-Å radiation, the wavelength required for biological applications.
The CLS will instead use a laser pulse to bend the electrons. A 25-MeV electron beam, which can be stored in a desktop-sized ring, produces 1-Å radiation when undulated by a 1-μm laser. "It's straight physics," says structural proteomics researcher Peter Kuhn, professor of cell biology at the Scripps Research Institute, La Jolla, Calif.
Weis notes several advantages to the CLS over the rotating anode generators found in most X-ray crystallography laboratories. The generators emit monochromatic light that is too weak to probe complex structures, whereas the CLS is designed to be tunable, allowing users to select wavelengths. It also emits more intense light and is probably easier to maintain than rotating anodes, which contain many moving mechanical parts, Weis adds.
Ruth has founded Palo Alto-based Lyncean Technologies
According to Ruth, the Lyncean system "complements the major facilities with a source that can do a good fraction of what can be done at the large synchrotron, and in an individual station." But don't expect synchrotrons to become extinct, says Weis: Cutting-edge experiments will still require a trip to an advanced photon source.
- Aileen Constans