Simultaneous Femtosecond X-ray Spectroscopy and Diffraction of Photosystem II at Room Temperature

Abstract

Intense femtosecond X-ray pulses produced at the Linac Coherent Light Source (LCLS) were used for simultaneous X-ray diffraction (XRD) and X-ray emission spectroscopy (XES) of microcrystals of Photosystem II (PS II) at room temperature. This method probes the overall protein structure and the electronic structure of the Mn4CaO5 cluster in the oxygen-evolving complex of PS II. XRD data are presented from both the dark state (S1) and the first illuminated state (S2) of PS II. Our simultaneous XRD/XES study shows that the PS II crystals are intact during our measurements at the LCLS, not only with respect to the structure of PS II, but also with regard to the electronic structure of the highly radiation sensitive Mn4CaO5 cluster, opening new directions for future dynamics studies.

Ceramic micro-injection molded nozzles for serial femtosecond crystallography sample delivery

“…3,4 This method is opening new doors in structural biology, yielding atomic resolution structures from micrometer-sized crystals and smaller, radiation sensitive protein crystals, [5][6][7][8][9][10] as well as, enabling experiments to study fast structural protein dynamics. [11][12][13][14][15] Considering the destructive nature of the pulses, data collection is optimized by a serial approach, where a new crystal is placed in the beam for each X-ray pulse. The Linac Coherent Light Source (LCLS) FEL has the fastest repetition rate of all currently operational hard X-ray FELs at 120 Hz, but a much faster 4.5 MHz bunch mode will be implemented at a) Current address: Department of Physics, Arizona State University, P.O.…”

Stimulated Electronic X-Ray Raman Scattering

“…X-ray free electron lasers (XFELs) [5][6][7] with pulse durations in the fs range and unprecedented high intensities, hold the potential for transferring these techniques to the x-ray domain, to ultimately study the coherent interplay of electronic and vibrational degrees of freedom with high temporal and spatial resolution [8][9][10]. The high penetration depth of x rays, combined with the element and chemical sensitivity of inelastic x-ray scattering [11][12][13] could open pathways to temporally resolve complex dynamical processes such as energy transfer in light harvesting complexes or reaction dynamics of catalytic processes [14,15]. However, the cross section for x-ray Raman scattering is small compared to that in the visible spectral domain.…”

Determination of multiwavelength anomalous diffraction coefficients at high x-ray intensity

“…In the highintensity limit, for example, at the fluence of 5×10 12 photons/µm 2 , the measured c from fluorescence deviates from the calculated c by ∼10% near the peak around 8.6 keV, even though it shows a qualitatively similar trend to the calculated c. Figure 3 demonstrates that it is possible to determine the MAD coefficient c if one scans the photon energy and the fluence when performing the fluorescence measurement. With a high resolution in fluorescence spectra, one can observe different charge states [9] or changes of oxidation states [15], which might provide additional information on heavy atoms at high x-ray intensity. However, the proposed experimental scheme does not require high-resolution fluorescence spectra; instead, it is enough to distinguish emitted photons from light atoms and heavy atoms in order to be able to count fluorescence photons from heavy atoms only.…”

“…X-ray free-electron lasers (XFELs) [1,2,3,4], which feature ultraintense and ultrashort x-ray pulses, have brought us a new way of thinking about x-ray-matter interaction and have an impact on various scientific fields, such as atomic and molecular physics [5,6,7], x-ray optics [8], material science [9], astrophysics [10], and molecular biology [11,12,13,14,15]. Many collections and reviews on scientific achievements with XFELs are available [16,17,18], including the current special issue on "Frontiers of FEL Science.…”