We show that the speed of the chromophore photoisomerization of animal rhodopsins is not a relevant control knob for their light sensitivity. This result is at odds with the momentum-driven tunnelling rationale (i.e., assuming a one-dimensional Landau-Zener model for the decay: Zener, C. Non-Adiabatic Crossing of Energy Levels. Proc. R. Soc. London, Ser. A 1932, 137 (833), 696-702) holding that a faster nuclear motion through the conical intersection translates into a higher quantum yield and, thus, light sensitivity. Instead, a model based on the phase-matching of specific excited state vibrational modes should be considered. Using extensive semiclassical hybrid quantum mechanics/molecular mechanics trajectory computations to simulate the photoisomerization of three animal rhodopsin models (visual rhodopsin, squid rhodopsin and human melanopsin), we also demonstrate that phase-matching between three different modes (the reactive carbon and hydrogen twisting coordinates and the bond length alternation mode) is required to achieve high quantum yields. In fact, such "phase-matching" mechanism explains the computational results and provides a tool for the prediction of the photoisomerization outcome in retinal proteins.

El-Tahawy, M.M.T., Nenov, A., Weingart, O., Olivucci, M., Garavelli, M. (2018). Relationship between Excited State Lifetime and Isomerization Quantum Yield in Animal Rhodopsins: Beyond the One-Dimensional Landau-Zener Model. THE JOURNAL OF PHYSICAL CHEMISTRY LETTERS, 9(12), 3315-3322 [10.1021/acs.jpclett.8b01062].

Relationship between Excited State Lifetime and Isomerization Quantum Yield in Animal Rhodopsins: Beyond the One-Dimensional Landau-Zener Model

Olivucci, Massimo;
2018-01-01

Abstract

We show that the speed of the chromophore photoisomerization of animal rhodopsins is not a relevant control knob for their light sensitivity. This result is at odds with the momentum-driven tunnelling rationale (i.e., assuming a one-dimensional Landau-Zener model for the decay: Zener, C. Non-Adiabatic Crossing of Energy Levels. Proc. R. Soc. London, Ser. A 1932, 137 (833), 696-702) holding that a faster nuclear motion through the conical intersection translates into a higher quantum yield and, thus, light sensitivity. Instead, a model based on the phase-matching of specific excited state vibrational modes should be considered. Using extensive semiclassical hybrid quantum mechanics/molecular mechanics trajectory computations to simulate the photoisomerization of three animal rhodopsin models (visual rhodopsin, squid rhodopsin and human melanopsin), we also demonstrate that phase-matching between three different modes (the reactive carbon and hydrogen twisting coordinates and the bond length alternation mode) is required to achieve high quantum yields. In fact, such "phase-matching" mechanism explains the computational results and provides a tool for the prediction of the photoisomerization outcome in retinal proteins.
2018
El-Tahawy, M.M.T., Nenov, A., Weingart, O., Olivucci, M., Garavelli, M. (2018). Relationship between Excited State Lifetime and Isomerization Quantum Yield in Animal Rhodopsins: Beyond the One-Dimensional Landau-Zener Model. THE JOURNAL OF PHYSICAL CHEMISTRY LETTERS, 9(12), 3315-3322 [10.1021/acs.jpclett.8b01062].
File in questo prodotto:
File Dimensione Formato  
Relationship between Excited State Lifetime.pdf

non disponibili

Tipologia: PDF editoriale
Licenza: NON PUBBLICO - Accesso privato/ristretto
Dimensione 3.8 MB
Formato Adobe PDF
3.8 MB Adobe PDF   Visualizza/Apri   Richiedi una copia
OLIVUCCI-Relationship between excited-PMC AAM-PostPrint.pdf

accesso aperto

Descrizione: PMC Author Manuscripts
Tipologia: Post-print
Licenza: PUBBLICO - Pubblico con Copyright
Dimensione 1.39 MB
Formato Adobe PDF
1.39 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11365/1062021