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Effect of bicarbonate on the S 2 multiline EPR signal of the oxygen‐evolving complex in photosystem II membrane fragments
Author(s) -
Hulsebosch R.J,
Allakhverdiev S.I,
Klimov V.V,
Picorel R,
Hoff A.J
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)00163-x
Subject(s) - bicarbonate , photosystem ii , electron paramagnetic resonance , oxygen evolving complex , chemistry , oxygen , oxygen evolution , membrane , spinach , photochemistry , inorganic chemistry , photosynthesis , nuclear magnetic resonance , biochemistry , organic chemistry , physics , electrode , electrochemistry
Removal of bicarbonate from spinach photosystem II BBY particles by means of washing in a CO 2 ‐free medium results in the loss of their capability to accumulate the S 2 multiline EPR signal upon continuous illumination at 190 K. Addition of 1 mM NaHCO 3 before illumination leads to a 50–60% restoration of the multiline signal. Similarly, in BBY particles depleted of Mn by treatment with 1 M Tris‐HCl (pH 8.0) and 0.5 M MgCl 2 , re‐addition of MnCl 2 in the presence of 1 mM NaHCO 3 results in a partial restoration (∼30%) of the S 2 multiline EPR signal of the Mn cluster, while in the absence of NaHCO 3 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.