Photoinactivation of Photosystem II by flashing light

András Szilárd, László Sass, E̊va Hideg, Imre Vass

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Inhibition of Photosystem II (PS II) activity by single turnover visible light flashes was studied in thylakoid membranes isolated form spinach. Flash illumination results in decreased oxygen evolving activity of PS II, which effect is most pronounced when the water-oxidizing complex is in the S 2 and S3 states, and increases with increasing time delay between the subsequent flashes. By applying the fluorescent spin-trap DanePy, we detected the production of singlet oxygen, whose amount was increasing with increasing flash spacing. These findings were explained in the framework of a model, which assumes that recombination of the S2Q B - and S3Q B - states generate the triplet state of the reaction center chlorophyll and lead to the production of singlet oxygen.

Original languageEnglish
Pages (from-to)15-20
Number of pages6
JournalPhotosynthesis research
Issue number1-3
Publication statusPublished - Jun 1 2005



  • Low light effect
  • Photoinactivation
  • Photosystem II
  • S-states

ASJC Scopus subject areas

  • Biochemistry
  • Plant Science
  • Cell Biology

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