An advanced platform for structural biology
The BL18U1 microcrystallography beamline at SSRF is one of the five beamlines operated by the National Facility for Protein Science in Shanghai and the first microcrystallography beamline at a third-generation synchrotron light source in China. Designed for microcrystals and other challenging samples, BL18U1 has become an important platform for structural biology and crystallographic research.
High-quality beam, flexible energy, integrated instrumentation
BL18U1 combines advanced optical design with stable microbeam performance. At the sample position, it delivers a beam of about 9.8 μm horizontally and 4.6 μm vertically, providing suitable conditions for diffraction studies of protein microcrystals, membrane protein crystals, small-molecule crystals, and other difficult samples. With a tunable energy range of 5–18 keV, the beamline can meet different experimental needs and support absorption-edge measurements as well as anomalous diffraction experiments.
The experimental station is equipped with an MD2 microdiffractometer, a Pilatus 3 6M detector, a Rigaku ACTOR robotic sample changer, and a cryogenic cooling system. Together with the MXCuBE3 control system, these components enable precise sample alignment, efficient automated operation, rapid data acquisition, and streamlined data processing.
From routine diffraction to sulfur-SAD phasing
The study shows that BL18U1 can routinely provide high-quality diffraction data. In lysozyme experiments, the beamline achieved diffraction data to 1.28 Å resolution with excellent processing statistics. The beamline also demonstrated long-wavelength anomalous diffraction capability at 2.02 Å, enhanced anomalous signals from endogenous sulfur atoms enabled sulfur-SAD phasing, reliable electron density map calculation, and atomic model building.
Strong support for high-quality structure determination
By the end of 2024, data collected at BL18U1 had contributed to 1,687 macromolecular structures deposited in the Protein Data Bank, with most structures in the 1.5–2.5 Å high-resolution range. These results show that BL18U1 has consistently supported the determination of numerous high-quality crystal structures and plays an important role in structural biology and structure-based research at SSRF.
The complete study is via by DOI: https://doi.org/10.1007/s41365-026-01991-6
