Abstract
X-ray free-electron lasers (XFELs) enable novel experiments because of their high peak brilliance and femtosecond pulse duration. However, non-superconducting XFELs offer repetition rates of only 10–120 Hz, placing significant demands on beam time and sample consumption. We describe serial femtosecond crystallography experiments performed at the European XFEL, the first MHz repetition rate XFEL, delivering 1.128 MHz X-ray pulse trains at 10 Hz. Given the short spacing between pulses, damage caused by shock waves launched by one XFEL pulse on sample probed by subsequent pulses is a concern. To investigate this issue, we collected data from lysozyme microcrystals, exposed to a ~15 μm XFEL beam. Under these conditions, data quality is independent of whether the first or subsequent pulses of the train were used for data collection. We also analyzed a mixture of microcrystals of jack bean proteins, from which the structure of native, magnesium-containing concanavalin A was determined.
Highlights
X-ray free-electron lasers (XFELs) enable novel experiments because of their high peak brilliance and femtosecond pulse duration
We demonstrate here that it is possible to separate the data of the three types of protein crystals in such a microcrystalline mixture of jack bean proteins, and to determine the structures of the two concanavalins, using data collected at the first MHz XFEL
Full exploitation of the MHz repetition rate for SFX data collection requires three conditions to be fulfilled: (i) when using microjets for sample delivery, highintensity XFEL pulses induce explosions that generate a gap in the liquid jet[20] and a fresh section of the running jet must advance to the X-ray interaction region before arrival of the subsequent XFEL pulse. (ii) Sample that is exposed to an XFEL pulse should not have been exposed to X-rays from the previous pulse, as this can cause radiation damage. (iii) It has been shown that the impact of an XFEL pulse on the liquid jet may launch shock waves travelling upstream of the jet before onset of the explosion[20]
Summary
X-ray free-electron lasers (XFELs) enable novel experiments because of their high peak brilliance and femtosecond pulse duration. We describe serial femtosecond crystallography experiments performed at the European XFEL, the first MHz repetition rate XFEL, delivering 1.128 MHz X-ray pulse trains at 10 Hz. Given the short spacing between pulses, damage caused by shock waves launched by one XFEL pulse on sample probed by subsequent pulses is a concern. Given the short spacing between pulses, damage caused by shock waves launched by one XFEL pulse on sample probed by subsequent pulses is a concern To investigate this issue, we collected data from lysozyme microcrystals, exposed to a ~15 μm XFEL beam. The high intensity of the pulses enables the study of weakly scattering objects such as very small crystals[6,7,8] and the coherence of the beam enables the imaging of non-crystalline particles[9,10] In line with these transformative capabilities, demand for beam time at XFELs is very high. We demonstrate here that it is possible to separate the data of the three types of protein crystals in such a microcrystalline mixture of jack bean proteins (urease, concanavalin A and B), and to determine the structures of the two concanavalins, using data collected at the first MHz XFEL
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
