Calcium reconstitutes high rates of oxygen evolution in polypeptide depleted Photosystem II preparations

FEBS Letters

Babcock, Gerald T.¹  Yocum, Charles F.²  Ghanotakis, Demetrios F.² 

[1] Department of Chemistry, Michigan State University, East Lansing, MI 48824-1322, USA;Division of Biological Sciences, The University of Michigan, Ann Arbor, MI 48109-1048 USA

关键词: Photosystem II;    Oxygen evolution;    Polypeptide;    Calcium;    DCBQ;    2;    5-dichloro-p-benzoquinone;    DCMU;    3-(3;    4-dichlorophenyl)-1;    1-dimethylurea;    FeIIICN;    potassium ferricyanide;    Hepes;    N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid;    Mes;    4-morpholinoethane-sulfonic acid;    PS II;    Photosystem II;   

DOI  :  10.1016/0014-5793(84)80846-7

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Exposure of highly resolved Photosystem II preparations to 2 M NaCl produces an 80% inhibition of oxygen-evolution activity concomitant with extensive loss of two water-soluble polypeptides (23 and 17 kDa). Addition of Ca²⁺ to salt-washed PS II membranes causes an acceleration in the decay of Z^⨥, the primary donor to P-680⁺, and we show here that this acceleration is due to reconstitution of oxygen-evolution activity by Ca²⁺. Other cations (Mg²⁺, Mn²⁺, Sr²⁺) are much less effective in restoring oxygen evolution. On the basis of these observations we propose that Ca²⁺, perhaps in concert with the 23 kDa polypeptide, is an essential cofactor for electron transfer from the ‘S’-states to Z on the oxidizing side of PS II.

【 授权许可】

Unknown