Effect of bicarbonate on the S2 multiline EPR signal of the oxygen-evolving complex in photosystem II membrane fragments

R. J. Hulsebosch, S. I. Allakhverdiev, V. V. Klimov, R. Picorel, A. J. Hoff

    Research output: Contribution to journalArticlepeer-review

    13 Citations (Scopus)


    Removal of bicarbonate from spinach photosystem II BBY particles by means of washing in a CO2-free medium results in the loss of their capability to accumulate the S2 multiline EPR signal upon continuous illumination at 190 K. Addition of 1 mM NaHCO3 before illumination leads to a 50-60% restoration of the multiline signal. Similarly, in BBY particles depleted of Mn by treatment with 1 mM Tris-HCl (pH 8.0) and 0.5 M MgCl2, re-addition of MnCl2 in the presence of 1 mM NaHCO3 results in a partial restoration (~ 30%) of the S2 multiline EPR signal of the Mn cluster, while in the absence of NaHCO3 no restoration is observed. The results provide further evidence that bicarbonate is essential for maintaining the Mn-containing oxygen-evolving complex of PS II in a functionally active form.

    Original languageEnglish
    Pages (from-to)146-148
    Number of pages3
    JournalFEBS Letters
    Issue number3
    Publication statusPublished - Mar 13 1998


    • Bicarbonate
    • Donor side
    • Manganese
    • Multiline EPR signal
    • Photosystem II
    • S state

    ASJC Scopus subject areas

    • Biophysics
    • Structural Biology
    • Biochemistry
    • Molecular Biology
    • Genetics
    • Cell Biology


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