Redox Potential of the Primary Plastoquinone Electron Acceptor QAin Photosystem II fromThermosynechococcus elongatusDetermined by Spectroelectrochemistry

Biochemistry ◽  
2009 ◽  
Vol 48 (45) ◽  
pp. 10682-10684 ◽  
Author(s):  
Tadao Shibamoto ◽  
Yuki Kato ◽  
Miwa Sugiura ◽  
Tadashi Watanabe
Keyword(s):  
Photosystem Ii ◽  
Redox Potential ◽  
Electron Acceptor

scholarly journals Redox potential of the terminal quinone electron acceptor QB in photosystem II reveals the mechanism of electron transfer regulation

2015 ◽  
Vol 113 (3) ◽  
pp. 620-625 ◽  
Author(s):  
Yuki Kato ◽  
Ryo Nagao ◽  
Takumi Noguchi
Keyword(s):  
Electron Transfer ◽  
Photosystem Ii ◽  
Redox Potential ◽  
Electron Acceptor ◽  
Light Energy ◽  
Large Decrease ◽  
Difference Spectroscopy ◽  
Light Energy Conversion ◽  
First Time ◽  
Electron Transfers

Photosystem II (PSII) extracts electrons from water at a Mn4CaO5 cluster using light energy and then transfers them to two plastoquinones, the primary quinone electron acceptor QA and the secondary quinone electron acceptor QB. This forward electron transfer is an essential process in light energy conversion. Meanwhile, backward electron transfer is also significant in photoprotection of PSII proteins. Modulation of the redox potential (Em) gap of QA and QB mainly regulates the forward and backward electron transfers in PSII. However, the full scheme of electron transfer regulation remains unresolved due to the unknown Em value of QB. Here, for the first time (to our knowledge), the Em value of QB reduction was measured directly using spectroelectrochemistry in combination with light-induced Fourier transform infrared difference spectroscopy. The Em(QB−/QB) was determined to be approximately +90 mV and was virtually unaffected by depletion of the Mn4CaO5 cluster. This insensitivity of Em(QB−/QB), in combination with the known large upshift of Em(QA−/QA), explains the mechanism of PSII photoprotection with an impaired Mn4CaO5 cluster, in which a large decrease in the Em gap between QA and QB promotes rapid charge recombination via QA−.

scholarly journals Influence of the Redox Potential of the Primary Quinone Electron Acceptor on Photoinhibition in Photosystem II

2007 ◽  
Vol 282 (17) ◽  
pp. 12492-12502 ◽  
Author(s):  
Christian Fufezan ◽  
Christine M. Gross ◽  
Martin Sjödin ◽  
A. William Rutherford ◽  
Anja Krieger-Liszkay ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Redox Potential ◽  
Electron Acceptor

Species-dependence of the redox potential of the primary quinone electron acceptor QA in photosystem II verified by spectroelectrochemistry

FEBS Letters ◽  
2010 ◽  
Vol 584 (8) ◽  
pp. 1526-1530 ◽  
Author(s):  
Tadao Shibamoto ◽  
Yuki Kato ◽  
Ryo Nagao ◽  
Takuya Yamazaki ◽  
Tatsuya Tomo ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Redox Potential ◽  
Electron Acceptor

scholarly journals Structural Changes in the Acceptor Site of Photosystem II upon Ca2+/Sr2+ Exchange in the Mn4CaO5 Cluster Site and the Possible Long-Range Interactions

Biomolecules ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 371
Author(s):  
Koua
Keyword(s):  
Crystal Structure ◽  
Photosystem Ii ◽  
Long Range ◽  
Electron Acceptor ◽  
Structural Changes ◽  
Acceptor Site ◽  
Oxygen Evolving Complex ◽  
Long Range Interactions ◽  
Structural Perturbations ◽  
Oxygen Evolving

The Mn4CaO5 cluster site in the oxygen-evolving complex (OEC) of photosystem II (PSII) undergoes structural perturbations, such as those induced by Ca2+/Sr2+ exchanges or Ca/Mn removal. These changes have been known to induce long-range positive shifts (between +30 and +150 mV) in the redox potential of the primary quinone electron acceptor plastoquinone A (QA), which is located 40 Å from the OEC. To further investigate these effects, we reanalyzed the crystal structure of Sr-PSII resolved at 2.1 Å and compared it with the native Ca-PSII resolved at 1.9 Å. Here, we focus on the acceptor site and report the possible long-range interactions between the donor, Mn4Ca(Sr)O5 cluster, and acceptor sites.

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