Three-dimensional view of ultrafast dynamics in photoexcited bacteriorhodopsin
Abstract
Bacteriorhodopsin (bR) is a light-driven proton pump. We use time-resolved crystallography at an X-ray free-electron laser to follow the structural changes in multiphoton-excited bR from 250 femtoseconds to 10 picoseconds. Quantum chemistry and ultrafast spectroscopy allow identifying a sequential two-photon absorption process, leading to excitation of a tryptophan residue flanking the retinal chromophore, as a first manifestation of multi-photon effects. We resolve distinct stages in the structural dynamics of the all-trans retinal in photoexcited bR to a highly twisted 13-cis conformation. Other active site sub-picosecond rearrangements include correlated vibrational motions of the electronically excited retinal chromophore, the surrounding amino acids and water molecules as well as their hydrogen bonding network. These results show that this extended photo-active network forms an electronically and vibrationally coupled system in bR, and most likely in all retinal proteins.
Keywords
Cite
@article{arxiv.1905.09002,
title = {Three-dimensional view of ultrafast dynamics in photoexcited bacteriorhodopsin},
author = {Gabriela Nass Kovacs and Jacques-Philippe Colletier and Marie Grünbein and Yang Yang and Till Stensitzki and Alexander Batyuk and Sergio Carbajo and R Doak and David Ehrenberg and Lutz Foucar and Raphael Gasper and Alexander Gorel and Mario Hilpert and Marco Kloos and Jason Koglin and Jochen Reinstein and Christopher Roome and Ramona Schlesinger and Matthew Seaberg and Robert Shoeman and Miriam Stricker and Sébastien Boutet and Stefan Haacke and Joachim Heberle and Karsten Heyne and Tatiana Domratcheva and Thomas Barends and Ilme Schlichting},
journal= {arXiv preprint arXiv:1905.09002},
year = {2019}
}