pH dependence of the multiline, manganese EPR signal for the 'S2' state in PS II particles. Absence of proton release during the S1 → S2 electron transfer step of the oxygen evolving system

Reddy Damoder, G Charles Dismukes

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20 Citations (Scopus)


The pH dependence of oxygen evolution rates, 2,6-dichlorophenolindophenol (DCIP) reduction rates and the intensity of the multiline manganese EPR signal associated with the S2 Kok state has been studied using oxygen-evolving spinach (PS) II particles. The oxygen evolution and DCIP reduction rates are found to be very sensitive to pH, with the maximal rates occuring at pH 6.5-7.0. Both the rate and yield of the S1 multiline manganese EPR signal intensity, produced by single flash excitation at room temperature or by continuous illumination at 200 K, are found to be independent of pH, indicating that no proton is released from this manganese site during the S1 → S1 electron transfer. These results agree with those from other laboratories showing no proton release on this transition, but using techniques monitoring other species.

Original languageEnglish
Pages (from-to)157-161
Number of pages5
JournalFEBS Letters
Issue number1
Publication statusPublished - Aug 20 1984



  • Electron transfer
  • Manganese EPR
  • Photosynthetic oxygen evolution
  • Photosynthetic water oxidation
  • Photosystem II
  • S multiline EPR signal

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

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