Formation of the High-Spin S2State Related to the Extrinsic Proteins in the Oxygen Evolving Complex of Photosystem II

Shota Taguchi, Liangliang Shen, Guangye Han, Yasufumi Umena, Jian Ren Shen, Takumi Noguchi, Hiroyuki Mino

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1 Citation (Scopus)


The high-spin S2 state was investigated with photosystem II (PSII) from spinach, Thermosynechococcus vulcanus, and Cyanidioschyzon merolae. In extrinsic protein-depleted PSII, high-spin electron paramagnetic resonance (EPR) signals were not detected in either species, whereas all species showed g ∼5 signals in the presence of a high concentration of Ca2+ instead of the multiline signal. In the intact and PsbP/Q-depleted PSII from spinach, the g = 4.1 EPR signal was detected. These results show that formation of the high-spin S2 state of the manganese cluster is regulated by the extrinsic proteins through a charge located near the Mn4 atom in the Mn4CaO5 cluster but is independent of the intrinsic proteins. The shift to the g ∼5 state is caused by tilting of the z-axis in the Mn4 coordinates through hydrogen bonds or external divalent cations. The structural modification may allow insertion of an oxygen atom during the S2-to-S3 transition.

Original languageEnglish
Pages (from-to)8908-8913
Number of pages6
JournalJournal of Physical Chemistry Letters
Issue number20
Publication statusPublished - Oct 15 2020

ASJC Scopus subject areas

  • Materials Science(all)
  • Physical and Theoretical Chemistry


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