Radiation Damage in XFEL: Case study from the oxygen-evolving complex of Photosystem II.
Structural changes induced by radiation damage in X-ray crystallography hinder the ability to understand the structure/function relationship in chemical reactions. Serial femtosecond crystallography overcomes this problem by exposing the sample to very short and intense laser pulse leading to measurement before destruction. Here we use molecular modeling to map the radiation damage during the 10-50 fs to the intensity, the energy and the time duration of the laser pulse on the oxygen-evolving complex (OEC) of photosystem II. In the model, the nuclei move classically in a fully quantum potential created by electron density under the effect of strong laser pulse in the Ehrenfest dynamics regime. The results show that the Mn-Mn and Mn-Ca distances are less affected by radiation damage due to the their heavy masses, while one μ-oxo bridge (O5) moves significantly. The radiation damage may induce conformational changes of the water ligands but only bond elongation for the amino acids ligands. These effects are relatively intensity independent from 1016to 1017W/cm2, but changes increase dramatically if the beam intensity is increased to 1018W/cm2. In addition, the self amplified spontaneous emission (SASE) nature of the laser beam does not affect the dynamics of the ions.
Department of Physics, City College of New York, New York, New York 10031, United States.|Center for Photonics and Smart Materials, Zewail City of Science and Technology, Sheikh Zayed District, 6th of October City, 12588 Giza, Egypt.
Muhamed
M
Amin
Center for Photonics and Smart Materials, Zewail City of Science and Technology, Sheikh Zayed District, 6th of October City, 12588 Giza, Egypt.
Ashraf
A
Badawi
Center for Photonics and Smart Materials, Zewail City of Science and Technology, Sheikh Zayed District, 6th of October City, 12588 Giza, Egypt.
S S
SS
Obayya