We have found that copper(II) ions at about equimolar Cu2+/photosystem II (PS II) reaction center proportions stimulate oxygen evolution nearly twofold. This high affinity Cu-binding site is different from the binding sites of Mn and Ca ions. The analysis of the Cu2+ content in PS II preparations isolated from wild-type tobacco and a tobacco mutant deficient in light-harvesting complex suggests that Cu2+ may be a native component of PS II and may take part in the oxygen evolution process. At higher concentrations, Cu2+ ions inhibit oxygen evolution and quench fluorescence.

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http://dx.doi.org/10.1515/znc-2002-9-1016DOI Listing

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