High-Pressure Modulation of Primary Photosynthetic Reactions

Erko Jalviste, Kõu Timpmann, Manoop Chenchiliyan, Liina Kangur, Michael R. Jones, Arvi Freiberg

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


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.

Original languageEnglish
Pages (from-to)718-726
Number of pages9
JournalJournal of Physical Chemistry B
Issue number5
StatePublished - 6 Feb 2020
Externally publishedYes

Bibliographical note

Publisher Copyright:
Copyright © 2020 American Chemical Society.


Dive into the research topics of 'High-Pressure Modulation of Primary Photosynthetic Reactions'. Together they form a unique fingerprint.

Cite this