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

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