Open AccessZinc-inhibited Electron Transport of Photosynthesis in Isolated Barley Chloroplasts
Author(s) -
Baishnab C. Tripathy,
Prasanna Mohanty
Publication year - 1980
Publication title -
plant physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.554
H-Index - 312
eISSN - 1532-2548
pISSN - 0032-0889
DOI - 10.1104/pp.66.6.1174
Subject(s) - photosystem ii , hydroxylamine , chloroplast , photosystem i , p700 , electron transport chain , chemistry , photosynthesis , light harvesting complexes of green plants , photophosphorylation , molar concentration , hordeum vulgare , hill reaction , photosystem , chlorophyll , photochemistry , biochemistry , biology , botany , organic chemistry , poaceae , gene
In isolated barley chloroplasts, the presence of 2 millimolar ZnSO(4) inhibits the electron transport activity of photosystem II, as measured by photoreduction of dichlorophenolindophenol, O(2) evolution, and chlorophyll a fluorescence. The inhibition of photosystem II activity can be restored by the addition of the electron donor hydroxylamine or diphenylcarbazide, but not by benzidine and MnCl(2). These observations suggest that Zn inhibits electron flow at the oxidizing side of photosystem II at a site prior to the electron donating site(s) of hydroxylamine and diphenylcarbazide. No inhibition of photosystem I-dependent electron transport by 3 millimolar ZnSO(4) is observed. However, with concentrations of ZnSO(4) above 5 millimolar, photosystem I activity is partially inactivated. Washing Zn(2+)-treated chloroplasts partially restores the O(2)-evolving activity.
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