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

FEBS Letters - 1984
Demetrios F. Ghanotakis1, Gerald T. Babcock2, Charles F. Yocum1
1Division of Biological Sciences, The University of Michigan, Ann Arbor, MI 48109-1048 USA
2Department of Chemistry, Michigan State University, East Lansing, MI 48824-1322 USA

Tóm tắt

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.

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Tài liệu tham khảo

Ghanotakis D.F. Babcock G.T. and Yocum C.F. (1983) submitted. 10.1093/oxfordjournals.pcp.a076571 10.1016/0005-2728(82)90271-7 10.1016/B978-0-12-372360-4.50029-8 10.1016/0014-5793(83)80154-9 Chua N.H., 1980, Methods in Enzymology, 434 10.1016/0005-2728(82)90115-3 10.1016/0005-2728(78)90061-0 10.1016/0014-5793(83)80222-1 10.1104/pp.73.2.309 Yamashita T., 1974, Plant Cell Physiol., 15, 69
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