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Time-resolved serial crystallography at XFELs reveals ultrafast photochemical reactions, but high laser densities can cause photodamage to biological samples. Here, the authors study the early K-intermediate in bacteriorhodopsin at high power, showing overall conformation remains robust over a wide range.

The local X-ray-induced dynamics that occur in protein crystals during serial femtosecond crystallography (SFX) measurements at XFELs are not well understood. Here the authors performed a time-resolved X-ray pump X-ray probe SFX experiment, and they observe distinct structural changes in the disulfide bridges and peptide backbone of proteins; complementing theoretical approaches allow them to further characterize the details of the X-ray induced ionization and local structural dynamics.

rsEGFP2 is a reversibly photoswitchable fluorescent protein used in super-resolution light microscopy. Here the authors present the structure of an rsEGFP2 ground-state intermediate after excited state-decay that was obtained by nanosecond time-resolved serial femtosecond crystallography at an X-ray free electron laser, and time-resolved absorption spectroscopy measurements complement their structural analysis.

Ultrafast time-resolved serial femtosecond crystallography is used to investigate a photodissociation reaction in a protein, revealing the strong impact of the pump laser fluence on the structural changes  and the reaction mechanism.

X-ray fee-electron lasers (XFELs) enable time-resolved crystallography experiments and the structure determination of proteins with little or no radiation damage. However currently it is unknown whether the designated 4.5 MHz maximum pulse rate for the European XFEL could lead to sample damage caused by shock waves from preceding pulses. Here, the authors address this question by performing a X-ray pump X-ray probe experiment on haemoglobin microcrystals at the Stanford XFEL facility that mimics the 4.5 MHz data collection mode and observe structural changes and a drop in diffraction data quality of the crystals.

Trypanosoma brucei inosine-5′-monophosphate dehydrogenase (IMPDH) is an enzyme in the guanine nucleotide biosynthesis pathway and of interest as a drug target. Here the authors present the 2.8 Å room temperature structure of TbIMPDH determined by utilizing X-ray free-electron laser radiation and crystals that were grown in insect cells and find that ATP and GMP are bound at the canonical sites of the Bateman domains.

Femtosecond crystallography with an X-ray free-electron laser is used to analyse micrometre-sized protein crystals, generating a high-resolution structure of the protein without previous knowledge of what it looks like.

Lipidic sponge phase crystallization yields membrane protein microcrystals that can be injected into an X-ray free electron laser beam, yielding diffraction patterns that can be processed to recover the crystal structure.

Researchers describe a mechanism capable of compressing fast and intense X-ray pulses through the rapid loss of crystalline periodicity. It is hoped that this concept, combined with X-ray free-electron laser technology, will allow scientists to obtain structural information at atomic resolutions.

Protein serial crystallography at X-ray free-electron lasers (XFELs) is a powerful technique for structure determination. Here, authors present a device for sample delivery designed to abate challenges to non-specialists allowing for compound screening.

Photopharmacology manipulates the biological activity of small molecules by light. Using an X-ray laser, the authors follow the release of the drug azo-combretastatin A4 from tubulin and the concomitant structural changes over nine orders of magnitude in time.

One picosecond after photoactivation, isomerized retinal pulls away from half of its numerous interactions with its binding pocket, and the excess of the photon energy is released through an anisotropic protein breathing motion in the direction of the extracellular space.

Serial femtosecond crystallography is an X-ray free-electron-laser-based method that uses X-ray bursts to determine protein structures. Here the authors present the structure of a photosynthetic reaction centre, an integral membrane protein, achieved with no sign of X-ray-induced radiation damage.

A charge-integrating pixel-array detector called JUNGFRAU enables the collection of highly accurate X-ray crystallography data at synchrotron sources at unprecedented speeds.

Crystallographic ‘snapshots’ taken at intervals of femtoseconds to milliseconds after activation show how a light-activated sodium pump carries sodium ions across the cell membrane.

X-ray free-electron lasers produce bright femtosecond X-ray pulses. Here, the authors use a two-colour X-ray free-electron laser beam for simultaneous two-wavelength data collection and show that protein structures can be determined with multiple wavelength anomalous dispersion phasing, which is important for difficult-to-phase projects.

Providing detailed structural descriptions of the ultrafast photochemical events that occur in light-sensitive proteins is key to their understanding. Now, excited-state structures in the reversibly switchable fluorescent protein rsEGFP2 have been solved by time-resolved crystallography using an X-ray laser. These structures enabled the design of a mutant with improved photoswitching quantum yields.

X-ray-induced explosions in water drops, examined using time-resolved imaging, show interacting high-speed liquid and vapour flows. This type of X-ray absorption dynamics is predictable and may be used for inducing particular dynamical liquid states.

The first lasing results at SwissFEL, an X-ray free-electron laser, are presented, highlighting the facility’s unique capabilities. A general comparison to other major facilities is also provided.

The start-up of the new femtosecond hard X-ray laser facility in Stanford, the Linac Coherent Light Source, has brought high expectations for a new era for biological imaging. The intense, ultrashort X-ray pulses allow diffraction imaging of small structures before radiation damage occurs. This new capability is tested for the problem of structure determination from nanocrystals of macromolecules that cannot be grown in large crystals. Over three million diffraction patterns were collected from a stream of nanocrystals of the membrane protein complex photosystem I, which allowed the assembly of a three-dimensional data set for this protein, and proves the concept of this imaging technique.

Expression of a protein in Sf9 insect cells at high concentration triggers formation of in vivo crystals that can be analyzed by serial femtosecond X-ray crystallography.

Femtosecond X-ray pulses were used to obtain diffraction data on photosystem II, revealing conformational changes as the complex transitions from the dark S₁ state to the double-pumped S₃ state; the time-resolved serial femtosecond crystallography technique enables structural determination of protein conformations that are highly prone to traditional radiation damage.