Bicarbonate requirement for the donor side of photosystem II

V. V. Klimov, S. I. Allakhverdiev, Ya M. Feyziev, S. V. Baranov

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84 Citations (Scopus)


Suppression of electron flow (and its subsequent restoration with 3-10 mM NaHCO3) on the donor side of photosystem II is shown upon either a partial depletion of pea subchloroplast membranes in bicarbonate or the addition of 5-20 μM formate. At higher concentrations (5 mM) formate induces the known 'bicarbonate effect' on the acceptor side of photosystem II. In preparations depleted of manganese the restoration of electron flow with 0.1-0.2 μM MnCl2 (2-4 Mn per photosystem II reaction center) occurs only in the presence of bicarbonate and it is accompanied by an increased functional binding of manganese. Restoration of electron flow with diphenylcarbazide or NH2OH does not require the addition of NaHCO3. It is suggested that bicarbonate participates in the formation of the Mn-cluster capable of water oxidation or serves as a substrate for the water-oxidizing center.

Original languageEnglish
Pages (from-to)251-255
Number of pages5
JournalFEBS Letters
Issue number3
Publication statusPublished - Apr 24 1995
Externally publishedYes


  • Bicarbonate
  • Donor side
  • Manganese
  • Photosystem II

ASJC Scopus subject areas

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


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