Structural dynamics in proteins induced by and probed with X-ray free-electron laser pulses

• DOI: 10.1038/s41467-020-15610-4
• Publication Date: 2020-04-14T10:02:56Z
• Authors: Karol Nass; Alexander Gorel; Malik M. Abdullah; Andrew V. Martin; Marco Kloos; Agostino Marinelli; Andrew Aquila; Thomas R. M. Barends; Franz-Josef Decker; R. Bruce Doak; Lutz Foucar; Elisabeth Hartmann; Mario Hilpert; Mark S. Hunter; Zoltan Jurek; Jason E. Koglin; Alexander Kozlov; Alberto A. Lutman; Gabriela Nass Kovacs; Christopher M. Roome; Robert L. Shoeman; Robin Santra; Harry M. Quiney; Beata Ziaja; Sébastien Boutet; Ilme Schlichting
• Keywords: radiation damage; Free electron model; Free-electron laser

X-ray free-electron lasers (XFELs) enable crystallographic structure determination beyond the limitations imposed upon synchrotron measurements by radiation damage. The need for very short XFEL pulses is relieved through gating of Bragg diffraction loss crystalline order as damage progresses, but not if ionization events are spatially non-uniform due to underlying elemental distributions, in biological samples. Indeed, correlated movements iron and sulfur ions were observed XFEL-irradiated ferredoxin microcrystals using unusually long 80 fs. Here, we report a femtosecond time-resolved pump/X-ray probe experiment on protein nanocrystals. We observe changes backbone aromatic residues well disulfide bridges. Simulations show that latter's structural dynamics much slower than expected predicted high atomic charge states significant impact ion caging plasma electron screening. This indicates dense-environment effects can strongly affect local damage-induced dynamics.