Chloride requirement in photosystem II and anion effects in the S2' state of the oxygen evolving complex

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Hong Qian (Creator)
The University of North Carolina at Greensboro (UNCG )
Web Site:
Alice Haddy

Abstract: "The oxygen evolving complex (OEC) of photosystem II (PSII) requires chloride as a critical cofactor. The Cl- content of PSII was determined to be 1 Cl-/PSII by the AgCl colloid assay. The dissociation constant for Cl- in NaCl-washed PSII was determined using the Cl- sensitive microelectrode. Two classes of Cl- binding sites were found with Kd values of 53 mM and 4.2 mM. The effects of anions on the S2' oxidation state of the OEC were investigated using electron paramagnetic resonance spectroscopy. It was found that chloride was required for the formation of the S2' state. The effect of iodide, which is an activator of oxygen evolution at low concentrations and an inhibitor at high concentrations, was also tested. Both low and high concentrations of I- supported the formation of the S2' state, suggesting that I- inhibition occurs in some state higher than the S2' state."--Abstract from author supplied metadata.

Additional Information

Language: English
Date: 2006
oxygen evolving complex (OEC), photosystem II (PSII), chloride, cofactor,
Photosynthesis--Molecular aspects
Photosynthetic oxygen evolution

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