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Three-dimensional view of ultrafast dynamics in photoexcited bacteriorhodopsin

Abstract : Bacteriorhodopsin (bR) is a light-driven proton pump. The primary photochemical event uponlight absorption is isomerization of the retinal chromophore. Here we used time-resolvedcrystallography at an X-ray free-electron laser to follow the structural changes inmultiphoton-excited bR from 250 femtoseconds to 10 picoseconds. Quantum chemistry andultrafast spectroscopy were used to identify a sequential two-photon absorption process,leading to excitation of a tryptophan residueflanking the retinal chromophore, as afirstmanifestation of multiphoton effects. We resolve distinct stages in the structural dynamics ofthe all-transretinal in photoexcited bR to a highly twisted 13-cisconformation. Other activesite sub-picosecond rearrangements include correlated vibrational motions of the electro-nically excited retinal chromophore, the surrounding amino acids and water molecules as wellas their hydrogen bonding network. These results show that this extended photo-activenetwork forms an electronically and vibrationally coupled system in bR, and most likely in allretinal proteins.
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Contributor : Jacques-Philippe Colletier Connect in order to contact the contributor
Submitted on : Thursday, November 19, 2020 - 1:45:32 PM
Last modification on : Wednesday, December 1, 2021 - 3:32:10 PM
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Gabriela Nass Kovacs, Jacques-Philippe Colletier, Marie Luise Grünbein, Yang Yang, Till Stensitzki, et al.. Three-dimensional view of ultrafast dynamics in photoexcited bacteriorhodopsin. Nature Communications, Nature Publishing Group, 2019, 10 (1), ⟨10.1038/s41467-019-10758-0⟩. ⟨hal-03014303⟩



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