Towards uncovering the energetics of secondary electron transfer reactions in photosystem I

Stefano Santabarbara, Fabrice Rappaport, Kevin Edward Redding

Research output: Chapter in Book/Report/Conference proceedingChapter

Abstract

Phylloquinone (PhQ) acts as the secondary electron acceptor in the reaction centre of Photosystem I. At room temperature the semiquinone anion is oxidized with complex multiphasic kinetics by electron transfer to the iron-sulphur cluster FX. The two principle phases of the oxidation kinetics are characterized by lifetimes of 20 ns and 250 ns. The 20-ns phase is associated primarily with the oxidation of PhQB, which is bound by the PsaB subunit, and the 250-ns phase is associated with oxidation of PhQA, which is bound by the PsaA subunit. The difference of about one order of magnitude between the two oxidation lifetimes can be explained by considering the difference in the driving force for oxidation of the PhQA (ΔG0 > 0) and PhQB (ΔG0 < 0) semiquinone forms. Such an energetic scenario also promotes a transient electron transfer from PhQA to PhQB, with FX acting as an intermediary.

Original languageEnglish
Title of host publicationAdvanced Topics in Science and Technology in China
PublisherSpringer
Pages7-12
Number of pages6
DOIs
Publication statusPublished - Jan 1 2013

Publication series

NameAdvanced Topics in Science and Technology in China
ISSN (Print)1995-6819
ISSN (Electronic)1995-6827

Keywords

  • Clusters
  • Electron Transfer (ET)
  • Iron-sulphur
  • Photosystem I (PS I)
  • Phylloquinone
  • Reaction centre (RC)

ASJC Scopus subject areas

  • Engineering(all)
  • Chemical Engineering(all)
  • General

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  • Cite this

    Santabarbara, S., Rappaport, F., & Redding, K. E. (2013). Towards uncovering the energetics of secondary electron transfer reactions in photosystem I. In Advanced Topics in Science and Technology in China (pp. 7-12). (Advanced Topics in Science and Technology in China). Springer. https://doi.org/10.1007/978-3-642-32034-7_2