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Retinal chromophore charge delocalization and confinement explain the extreme photophysics of Neorhodopsin.

Riccardo PalomboLeonardo BarneschiLaura Pedraza-GonzálezDaniele PadulaIgor SchapiroMassimo Olivucci
Published in: Nature communications (2022)
The understanding of how the rhodopsin sequence can be modified to exactly modulate the spectroscopic properties of its retinal chromophore, is a prerequisite for the rational design of more effective optogenetic tools. One key problem is that of establishing the rules to be satisfied for achieving highly fluorescent rhodopsins with a near infrared absorption. In the present paper we use multi-configurational quantum chemistry to construct a computer model of a recently discovered natural rhodopsin, Neorhodopsin, displaying exactly such properties. We show that the model, that successfully replicates the relevant experimental observables, unveils a geometrical and electronic structure of the chromophore featuring a highly diffuse charge distribution along its conjugated chain. The same model reveals that a charge confinement process occurring along the chromophore excited state isomerization coordinate, is the primary cause of the observed fluorescence enhancement.
Keyphrases
  • optical coherence tomography
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  • climate change
  • photodynamic therapy
  • machine learning
  • energy transfer