Proxima 1, a New Beamline on the Third Generation SR Source SOLEIL Combining PX and Single‐Crystal BioXAS

We describe the main characteristics of the PROXIMA 1 beamline at the third generation synchrotron radiation (SR) facility SOLEIL in France. This beamline was designed for macromolecular crystallography, in particular combined MAD/SAD and BioXAS measurements on single crystals with X‐ray energies in the 5–15 keV range. An advanced system for beam line diagnostics, alignment and optimization is being developed. The overall design is oriented toward joint accurate data collection by the two techniques. It is well known that combination of PX and BioXAS adds atomic resolution to low and medium resolution PX data on metal centers in metalloproteins. Moreover we suggest probing systematically the redox state of metalloproteins with high quality XAS measurements in order to detect photoreduction processes.