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

FEBS Letters

Hoff, A.J¹  Klimov, V.V²  Picorel, R³  Allakhverdiev, S.I²  Hulsebosch, R.J¹ 

[1] Department of Biophysics, Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands;Institute of Soil Science and Photosynthesis, Russian Academy of Sciences, Pushchino, Moscow Region 142292, Russia;Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Cientificas, Apartado 202, E-50080 Zaragoza, Spain

关键词: Bicarbonate;    Donor side;    Manganese;    Multiline EPR signal;    Photosystem II;    S2 state;    PS II;    photosystem II;    OEC;    oxygen-evolving complex;   

DOI  :  10.1016/S0014-5793(98)00163-X

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

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 M 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.

【 授权许可】

Unknown