Discrete extraction of the Ca atom functional for O2 evolution in higher plant photosystem II by a simple low pH treatment

FEBS Letters

Ono, Taka-aki¹  Inoue, Yorinao¹ 

[1] Solar Energy Research Group, The Institute of Physical and Chemical Research (RIKEN), Wako, Saitama 351-01, Japan

关键词: Oxygen evolution;    Photosystem II membrane;    Ca2+ extraction;    Low pH treatment;    16 kDa protein;    24 kDa protein;    33 kDa protein;    PS;    photosystem;    Mes;    2-(N-morpholino)-ethanesulfonic acid;    DCIP;    2;    6-dichlorophenolindophenol;    DPC;    1;    5-diphenylcarbazide;    SDS-PAGE;    SDS-polyacrylamide gel electrophoresis;   

DOI  :  10.1016/0014-5793(88)80886-X

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Treatment of spinach PS II membranes with a citrate solution at pH 3.0 totally inactivated O₂ evolution concomitant with a 50% decrease in Ca abundance. Notably, neither the abundance of Mn and extrinsic proteins nor the activity of DPC photooxidation was at all affected by the treatment. The treated membranes evolved O₂ at a high rate in the presence of exogenous Ca²⁺, but the activity was sensitive to EDTA. However, when the treated membranes were incubated with Ca²⁺ for a few tens of minutes, the O₂-evolving activity became EDTA-resistant, suggesting a firm re-ligation of Ca²⁺ to the Ca-binding site. It was indicated that spinach PS II contains two Ca atoms per reaction center, and that the low pH citrate treatment selectively removes one of the two Ca atoms that is specifically functional for O₂ evolution, even in the presence of all three extrinsic proteins.

【 授权许可】

Unknown