The Macromolecular Femtosecond Crystallography Instrument at the Linac Coherent Light Source

Abstract

The Macromolecular Femtosecond Crystallography (MFX) instrument at the Linac Coherent Light Source (LCLS) is the seventh and newest instrument at the world's first hard X-ray free-electron laser. It was designed with a primary focus on structural biology, employing the ultrafast pulses of X-rays from LCLS at atmospheric conditions to overcome radiation damage limitations in biological measurements. It is also capable of performing various time-resolved measurements. The MFX design consists of a versatile base system capable of supporting multiple methods, techniques and experimental endstations. The primary techniques supported are forward scattering and crystallography, with capabilities for various spectroscopic methods and time-resolved measurements. The location of the MFX instrument allows for utilization of multiplexing methods, increasing user access to LCLS by running multiple experiments simultaneously.

Near-Physiological-Temperature Serial Femtosecond X-ray Crystallography Reveals Novel Conformations of SARS-CoV-2 Main Protease Active Site for Improved Drug Repurposing

“…S27 ). The diffraction data collected remotely at the MFX instrument of the LCLS at SLAC National Laboratory, Menlo Park, CA (Sierra et al, 2019) ( Supplementary Methods: Data Collection and Analysis for SFX studies at LCLS ). We used an Mpro structure determined at ambient-temperature using a rotating anode home X-ray source (PDB ID: 6WQF; Kneller et al, 2020) as our initial molecular replacement search model for structure determination.…”

“…Linac Coherent Light Source (LCLS) with its ultrafast and ultrabright pulses enables outrunning secondary radiation damage. The updated high-throughput Macromolecular Femtosecond Crystallography (MFX) instrument of LCLS that is equipped with the new autoranging epix10k 2-megapixel (ePix10k2M) detector that provides a dynamic range of eleven thousand 8keV photons in fixed low gain mode to collect secondary radiation-damage-free structural data from Mpro microcrystals remotely at ambient-temperature (Sierra et al, 2019; Blaj et al, 2019; Van Driel et al, 2020).…”

Applications and Limits of Time-to-Energy Mapping of Protein Crystal Diffraction Using Energy-Chirped Polychromatic XFEL Pulses

“…For each bin, BW req was calculated at resolutions between 0.9 and 10 Å and for effective mosaic spread values between 0.05-0.5 • using Equation 1 (Figure 4a). As mentioned above, the effective mosaic spread is a sum of the beam convergence and mosaicity contributions: at XFEL facilities, beam convergence at around 9 keV ranges from a few microradians (on the order of 10 −4 degrees) [51][52][53] for the unfocused beam, to tens of microradians if KB mirrors (e.g., ≈ 47 µrad ≈ 0.002 • [54]) or compound refractive lenses (e.g., ≈ 91 µrad ≈ 0.005 • [55]) are used for focusing. As this is considerably smaller than the mosaic spread of protein crystals, the latter is the determining factor.…”

Pump-Probe Time-Resolved Serial Femtosecond Crystallography at SACLA: Current Status and Data Collection Strategies

“…Sample delivery in SFX requires a thin stream with a high density of microcrystals to ensure a high hit rate; however, it is prone to clogging the nozzle of an injector. A helium atmosphere environment allows for the easy replacement of an injector and provides more flexibility in setting devices when compared to a vacuum environment, thus facilitating SFX data collection [17]. This experimental setup (Diverse Application Platform for Hard X-ray diffractioN In SACLA (DAPHNIS)), which consists of a helium chamber, a detector, an injector manipulator, and microscopes for the alignment of sample position, has been used for SFX experiments since 2013 [16].…”