High-Pressure Modulation of Primary Photosynthetic Reactions
(2020) In Journal of Physical Chemistry B 124(5). p.718-726- Abstract
Photochemical charge separation is key to biological solar energy conversion. Although many features of this highly quantum-efficient process have been described, others remain poorly understood. Herein, ultrafast fluorescence barospectroscopy is used for the first time to obtain insights into the mechanism of primary charge separation in a YM210W mutant bacterial reaction center under novel surrounding modulating conditions. Over a range of applied hydrostatic pressures reaching 10 kbar, the rate of primary charge separation monotonously increased and that of the electron transfer to secondary acceptor decreased. While the inferred free energy gap for charge separation generally narrowed with increasing pressure, a pressure-induced... (More)
Photochemical charge separation is key to biological solar energy conversion. Although many features of this highly quantum-efficient process have been described, others remain poorly understood. Herein, ultrafast fluorescence barospectroscopy is used for the first time to obtain insights into the mechanism of primary charge separation in a YM210W mutant bacterial reaction center under novel surrounding modulating conditions. Over a range of applied hydrostatic pressures reaching 10 kbar, the rate of primary charge separation monotonously increased and that of the electron transfer to secondary acceptor decreased. While the inferred free energy gap for charge separation generally narrowed with increasing pressure, a pressure-induced break of a protein-cofactor hydrogen bond observed at ∼2 kbar significantly (by 219 cm-1 or 27 meV) increased this gap, resulting in a drop in fluorescence. The findings strongly favor a model for primary charge separation that incorporates charge recombination and restoration of the excited primary pair state, over a purely sequential model. We show that the main reason for the almost threefold acceleration of the primary electron transfer rate is the pressure-induced increase of the electronic coupling energy, rather than a change of activation energy. We also conclude that across all applied pressures, the primary electron transfer in the mutant reaction center studied can be considered nonadiabatic, normal region, and thermally activated.
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- author
- Jalviste, Erko ; Timpmann, Kõu ; Chenchiliyan, Manoop LU ; Kangur, Liina ; Jones, Michael R. and Freiberg, Arvi
- publishing date
- 2020-02-06
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Journal of Physical Chemistry B
- volume
- 124
- issue
- 5
- pages
- 9 pages
- publisher
- The American Chemical Society (ACS)
- external identifiers
-
- pmid:31917566
- scopus:85079074902
- ISSN
- 1520-6106
- DOI
- 10.1021/acs.jpcb.9b09342
- language
- English
- LU publication?
- no
- additional info
- Publisher Copyright: Copyright © 2020 American Chemical Society.
- id
- 6b7584c4-4d2a-49e9-93dc-31ae92d495e9
- date added to LUP
- 2023-06-16 10:37:33
- date last changed
- 2024-04-05 20:31:08
@article{6b7584c4-4d2a-49e9-93dc-31ae92d495e9,
abstract = {{<p>Photochemical charge separation is key to biological solar energy conversion. Although many features of this highly quantum-efficient process have been described, others remain poorly understood. Herein, ultrafast fluorescence barospectroscopy is used for the first time to obtain insights into the mechanism of primary charge separation in a YM210W mutant bacterial reaction center under novel surrounding modulating conditions. Over a range of applied hydrostatic pressures reaching 10 kbar, the rate of primary charge separation monotonously increased and that of the electron transfer to secondary acceptor decreased. While the inferred free energy gap for charge separation generally narrowed with increasing pressure, a pressure-induced break of a protein-cofactor hydrogen bond observed at ∼2 kbar significantly (by 219 cm<sup>-1</sup> or 27 meV) increased this gap, resulting in a drop in fluorescence. The findings strongly favor a model for primary charge separation that incorporates charge recombination and restoration of the excited primary pair state, over a purely sequential model. We show that the main reason for the almost threefold acceleration of the primary electron transfer rate is the pressure-induced increase of the electronic coupling energy, rather than a change of activation energy. We also conclude that across all applied pressures, the primary electron transfer in the mutant reaction center studied can be considered nonadiabatic, normal region, and thermally activated.</p>}},
author = {{Jalviste, Erko and Timpmann, Kõu and Chenchiliyan, Manoop and Kangur, Liina and Jones, Michael R. and Freiberg, Arvi}},
issn = {{1520-6106}},
language = {{eng}},
month = {{02}},
number = {{5}},
pages = {{718--726}},
publisher = {{The American Chemical Society (ACS)}},
series = {{Journal of Physical Chemistry B}},
title = {{High-Pressure Modulation of Primary Photosynthetic Reactions}},
url = {{http://dx.doi.org/10.1021/acs.jpcb.9b09342}},
doi = {{10.1021/acs.jpcb.9b09342}},
volume = {{124}},
year = {{2020}},
}