Upgrade of BL-5C as a highly automated macromolecular crystallography beamline at Pohang Light Source II

Abstract

BL-5C is an in-vacuum undulator beamline dedicated to macromolecular crystallography (MX) at the 3 GeV Pohang Light Source II in Korea. The beamline delivers X-ray beams with a focal spot size of 200 µm × 40 µm (FWHM, H × V) over the energy range 6.5–16.5 keV. The measured flux is 7 × 1011 photons s−1 at 12.659 keV through an aperture size of 50 µm. The experimental station is newly equipped with the photon-counting detector EIGER 9M, the multi-axis micro-diffractometer MD2, and a robotic sample changer with a high-capacity dewar. These instruments enable the operation of this beamline as an automated MX beamline specialized in X-ray fragment screening. This beamline can collect more than 400 data sets a day without human intervention, and a difference map can be automatically calculated by using the data processing pipeline for ligand or fragment identification.