Energy optimization of a regular macromolecular crystallography beamline for ultra-high-resolution crystallography

Abstract

A practical method for operating existing undulator synchrotron beamlines at photon energies considerably higher than their standard operating range is described and applied at beamline 19-ID of the Structural Biology Center at the Advanced Photon Source enabling operation at 30keV. Adjustments to the undulator spectrum were critical to enhance the 30keV flux while reducing the lower-and higher-energy harmonic contamination. A Pd-coated mirror and Al attenuators acted as effective low-and high-bandpass filters. The resulting flux at 30keV, although significantly lower than with X-ray optics designed and optimized for this energy, allowed for accurate data collection on crystals of the small protein crambin to 0.38Å resolution.