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Toward Understanding Optical Properties of Amyloids: A Reaction Path and Nonadiabatic Dynamics Study

Grisanti, Luca; Sapunar, Marin; Hassanali, Ali; Došlić, Nađa (2020) Toward Understanding Optical Properties of Amyloids: A Reaction Path and Nonadiabatic Dynamics Study. Journal of the American Chemical Society, 142 (42). pp. 18042-18049. ISSN 0002-7863

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Amyloids have unique structural, chemical, and optical properties. Although much theoretical effort has been directed toward understanding amyloid nucleation, the understanding of their optical properties has remained rather limited. In particular, the photophysical mechanisms leading to near-UV excitation and characteristic blue-green luminescence in amyloid systems devoid of aromatic amino acids have not been resolved. We use ab initio static calculations and nonadiabatic dynamics simulations to study the excited electronic states of model amyloid-like peptides. We show that their photophysics is essentially governed by the multitude of nπ* states with excitation localized on the amide groups. The strong stabilization of the nπ* states with respect to the amide group deplanarization and the concomitant increase of the oscillator strength make excitation in the near-UV possible. With respect to emission, our dynamics simulations revealed that the amyloid cross β arrangement effectively hinders the nonradiative relaxation channels usually operative in proteins. Finally, we show that after relaxation of the photoexcited peptides toward the minimum of the different nπ* states, fluorescence takes place in the visible (green) part of the electromagnetic spectrum.

Item Type: Article
Uncontrolled Keywords: Amides ; Amyloids ; Peptides and proteins ;Fluorescence ;excited-state
Subjects: NATURAL SCIENCES > Physics > Atomic and Molecular Physics
NATURAL SCIENCES > Physics > Condensed Matter Physics
NATURAL SCIENCES > Chemistry > Physical Chemistry
NATURAL SCIENCES > Chemistry > Theoretical Chemistry
Divisions: Division of Physical Chemistry
Theoretical Physics Division
Project titleProject leaderProject codeProject type
Svjetlo na molekulama: istraživanje spregnute elektronske i nuklearne dinamike-LightMolNađa DošlićIP-2016-06-1142HRZZ
Depositing User: Luca Grisanti
Date Deposited: 22 Nov 2021 14:09
DOI: 10.1021/jacs.0c07134

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