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Classical and Entangled Two-Photon Absorption of Microbial Rhodopsin KR2 and Its Red-Shifted Mutantстатья
Дата последнего поиска статьи во внешних источниках: 15 октября 2025 г.
- Авторы: Kusochek P.A., Belov V.V., Aslopovsky V.R., Kazantsev S.A., Bochenkova A.V.
- Журнал: Russian Journal of Physical Chemistry A
- Том: 99
- Номер: 10
- Год издания: 2025
- Издательство: Pleiades Publishing, Ltd
- Местоположение издательства: Road Town, United Kingdom
- Первая страница: 2572
- Последняя страница: 2582
- DOI: 10.1134/S0036024425702073
- Аннотация: Microbial rhodopsin KR2 is a transmembrane photoactive protein that transports sodium ionsacross the membrane using light energy. KR2 is a promising tool for optogenetics, enabling optical control of neuronal activity. Here we explore the possibility of two-photon S0 → S1 excitation of KR2 and its red-shifted double mutant KR2 P219T/S254A with entangled and classical photon pairs. By using molecular dynamics simulations, a high-level XMCQDPT2-based QM/MM approach, and the sum-over-states formalism for calculating two-photon absorption (TPA) strengths, we show that the microbial rhodopsins intrinsically exhibit large classical TPA cross-sections due to a pronounced electron density redistribution upon the S0 → S1 transition. The nonclassical contribution turns out to be considerably larger than the classical counterpart in both KR2 and its double mutant, and the quantum entanglement of photon pairs further increases their transition strengths by one order of magnitude. Our calculations reproduce the experimental red shift in the absorption of the double mutant of KR2 and, while revealing only a slight increase in the classical TPA cross-section in KR2 P219T/S254A, show that its entangled TPA strength decreases. These variations, induced by alterations in the local electric field of the protein caused by the two amino acid replacements, can be attributed to changes in the permanent dipole moments between the ground and excited states. Our results demonstrate high tunability of the nonlinear photophysical properties of microbial rhodopsins, which can be used for the rational design of more efficient optogenetic tools upon two-photon excitation.
- Добавил в систему: Боченкова Анастасия Владимировна
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