Energetics of the S2 State Spin Isomers of the Oxygen-Evolving Complex of Photosystem II

David J. Vinyard, Sahr Khan, Mikhail Askerka, Victor S. Batista, Gary W Brudvig

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

The S2 redox intermediate of the oxygen-evolving complex in photosystem II is present as two spin isomers. The S = 1/2 isomer gives rise to a multiline electron paramagnetic resonance (EPR) signal at g = 2.0, whereas the S = 5/2 isomer exhibits a broad EPR signal at g = 4.1. The electronic structures of these isomers are known, but their role in the catalytic cycle of water oxidation remains unclear. We show that formation of the S = 1/2 state from the S = 5/2 state is exergonic at temperatures above 160 K. However, the S = 1/2 isomer decays to S1 more slowly than the S = 5/2 isomer. These differences support the hypotheses that the S3 state is formed via the S2 state S = 5/2 isomer and that the stabilized S2 state S = 1/2 isomer plays a role in minimizing S2QA - decay under light-limiting conditions.

Original languageEnglish
Pages (from-to)1020-1025
Number of pages6
JournalJournal of Physical Chemistry B
Volume121
Issue number5
DOIs
Publication statusPublished - Feb 9 2017

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Photosystem II Protein Complex
Isomers
isomers
Oxygen
oxygen
Paramagnetic resonance
electron paramagnetic resonance
decay
Electronic structure
electronic structure
Oxidation
oxidation
cycles
Water

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

Cite this

Energetics of the S2 State Spin Isomers of the Oxygen-Evolving Complex of Photosystem II. / Vinyard, David J.; Khan, Sahr; Askerka, Mikhail; Batista, Victor S.; Brudvig, Gary W.

In: Journal of Physical Chemistry B, Vol. 121, No. 5, 09.02.2017, p. 1020-1025.

Research output: Contribution to journalArticle

Vinyard, David J. ; Khan, Sahr ; Askerka, Mikhail ; Batista, Victor S. ; Brudvig, Gary W. / Energetics of the S2 State Spin Isomers of the Oxygen-Evolving Complex of Photosystem II. In: Journal of Physical Chemistry B. 2017 ; Vol. 121, No. 5. pp. 1020-1025.
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