From SLAC Today: "LCLS Offers New Method for Examining Membrane Proteins"

March 14, 2012
Diane Rezendes Khirallah

“Many membrane proteins serve as gateways in and out of the cell. Because they act as “traffic control” for infectious agents and disease-fighting drugs, they are the targets of more than 60 percent of all drugs on the market. Yet of the estimated 30,000 membrane proteins in the human body, scientists understand the detailed structures of only 18.

Now experiments at SLAC’s Linac Coherent Light Source (LCLS) have shown a promising new way to collect data on these elusive proteins. Researchers embedded tiny protein crystals in an oily paste that mimics the supportive environment of the cell membrane, and then hit them with a powerful X-ray laser to determine the protein’s structure. They reported their results in the March issue of Nature Methods.

Scientists embedded tiny protein crystals in an oily solution that mimics the supportive environment of the cell membrane, and then squirted them through a micro-jet into the path of a powerful X-ray laser. By analyzing the diffraction patterns made by X-rays scattering off the crystals, they were able to determine the protein’s structure. A key challenge was adjusting the viscosity of the oily solution, called a “lipidic sponge phase,” so it wouldn’t clog the micro-jet’s nozzle, shown here. Image courtesy Richard Neutze

Members of the large international research team represented more than a dozen institutions, including the Linac Coherent Light Source and Photon Ultrafast Laser Science and Engineering Center at SLAC; Gothenburg and Uppsala universities in Sweden; Arizona State University; the Center for Free-Electron Laser Science at DESY in Hamburg, Germany; DESY; the University of Hamburg; the Max Planck institutes for nuclear physics, extraterrestrial physics, semiconductor laboratory (Halbleiterlabor) and medical research; and the Advanced Light Source at the DOE’s Berkeley Lab.

See the full article here.

SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

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