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Chloride binding to photosystem II in the dark is in slow exchange
Author(s) -
Shachar-Hill Yair,
Beck Warren F.,
Brudvig Gary W.
Publication year - 1989
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(89)81035-x
Subject(s) - photosystem ii , chemistry , electron paramagnetic resonance , oxygen evolving complex , spinach , photochemistry , binding site , membrane , biophysics , photosynthesis , nuclear magnetic resonance , biochemistry , biology , physics
We have studied the 35 Cl − NMR line broadening in the presence of photosystem II (PS II) membranes from spinach in the dark. In the presence of NH 3 (which other work has shown to competitively inhibit chloride binding to PS II) we observed no decrease in 35 Cl − linewidths. We conclude that binding of Cl − to the O 2 evolving center in PS II in the dark (previously demonstrated by EPR) is in slow exchange on the NMR timescale. We assign the observed line broadening to interaction with non‐specific binding sites and with free paramagnetics.