| Abstract: | Treatment of the oxygen-evolving photosystem II preparation from the thermophilic cyanobacterium Synechococcus sp. with EDTA inhibited electron flow from Z to P680 and consequently induced a back electron flow from Q?a to P680+. The inhibition was reversed fully by Ca2+and partially by Mn2+ and Mg2+ when EDTA-treated preparations had been incubated with respective divalent metal cations for several minutes, whereas diphenylcarbazide had no effect on the recombination between q?a and P680+ in EDTA-treated preparations. It is concluded that Ca2+ is essential for electron transport from Z to P680. Oxygen evolution Electron transport Photosystem II Ca2+ Thermophilic cyanobacterium |
