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.

Serial crystallography (SX) makes a significant contribution for time-resolved studies and forms the base of structural analysis at room temperature, with minimal radiation damage. Even though X-ray free electron laser provides a femtosecond scale X-ray pulse, high accessibility of synchrotron facilities gives a merit for application of SX experiment. Therefore, we performed serial synchrotron crystallography (SSX) of lysozyme crystals at room-temperature. Both fixed target and injector-based methods were used for SX experiments to determine the structure of lysozyme crystals. Approximately 19,600 and 40,000 diffraction images were collected during 40 and 80 min, for fixed target and injectionbased methods, respectively in the SSX experiments. The 10 Hz synchrotron X-ray radiation of the 11C beamline of the Pohang accelerator laboratory was used and the crystal structures of lysozyme were determined at 1.89 Å and 1.80 Å resolutions, respectively. These results provide experimental clues for routine SX at room temperature in synchrotrons.