Making high-quality crystals large enough to usefully diffract X-rays is a major headache when attempting to determine protein structures by X-ray crystallography. Researchers prefer crystals that are 100–200 microns in size, with 5 microns being the smallest crystals that can be examined using a synchrotron X-ray source. More powerful X-rays provide better diffraction, but damage the crystals. Henry Chapman, from the Center for Free-Electron Laser Science in Hamburg and colleagues, fed a stream of tiny crystals, as small as 0.2 microns, into an X-ray beam generated by the Linac Coherent Light Source (LCLS)—a billion times more powerful than a synchrotron beam—but toggled the beam on for only a few femtoseconds at a time. The crystals exploded under the intense beam, but not before Chapman and colleagues collected a single diffraction pattern from each crystal. This was enough, given...
|Comparing Stanford'stwo X-ray generating Machines||MINIMUM CRYSTALSIZE viewable by each machine||PULSEDURATION(time neededto capture an image)||NUMBEROF IMAGESgenerated to solve a single structure||NUMBER OF UNDULATORS (housing athousandmagnets)||WAITLIST(once application is accepted)|
|Stanford SynchrotronRadiation Lightsource||5 µm||1–10 seconds||360||1 undulatorper X-ray beam||~1 month|
|Linac CoherentLight Source||0.2 µm||2–100 femotoseconds(10-15 of a second)||3,000,000||33 undulators(in a 120 m-long array||>1 year|