Upgrade of IMCA‐CAT Bending Magnet Beamline 17‐BM for Macromolecular Crystallography at the Advanced Photon Source

Pharmaceutical research depends on macromolecular crystallography as a tool in drug design and development. To solve the de novo three‐dimensional atomic structure of a protein, it is essential to know the phases of the X‐rays scattered by a protein crystal. Experimental phases can be obtained from multiwavelength anomalous dispersion (MAD) experiments. Dedicated to macromolecular crystallography, the IMCA‐CAT bending magnet beamline at sector 17 of the Advanced Photon Source (APS) was upgraded to provide the energy resolution required to successfully perform synchrotron radiation‐based MAD phasing of protein crystal structures. A collimating mirror was inserted into the beam path upstream of a double‐crystal monochromator, thus increasing the monochromatic beam throughput in a particular bandwidth without sacrificing the energy resolution of the system. The beam is focused horizontally by a sagittally bent crystal and vertically by a cylindrically bent mirror, delivering a beam at the sample of 130 μm (v...