Peroxynitrite inhibits electron transport on the acceptor side of higher plant photosystem II
| Autor: | Natalia Romero, Sergio González-Pérez, Thor Bernt Melø, Juan B. Arellano, Rafael Radi, Celia Quijano |
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| Rok vydání: | 2008 |
| Předmět: |
Chlorophyll
Photosystem II Biophysics Plastoquinone macromolecular substances Photochemistry Biochemistry law.invention Electron Transport chemistry.chemical_compound Spinacia oleracea law Peroxynitrous Acid Ferrous Compounds Electron paramagnetic resonance Molecular Biology Chlorophyll A Electron Spin Resonance Spectroscopy Quinones Oxygen evolution Photosystem II Protein Complex food and beverages DCMU Intracellular Membranes Oxidants Acceptor Electron transport chain Oxygen Spectrometry Fluorescence chemistry Diuron Peroxynitrite Polarography |
| Zdroj: | Archives of Biochemistry and Biophysics. 473:25-33 |
| ISSN: | 0003-9861 |
| Popis: | Peroxynitrite is a strong oxidant that has been proposed to form in chloroplasts. The interaction between peroxynitrite and photosystem II (PSII) has been investigated to determine whether this oxidant could be a hazard for PSII. Peroxynitrite is shown to inhibit oxygen evolution in PSII membranes in a dose-dependent manner. Analyses by PAM fluorimetry and EPR spectroscopy have demonstrated that the inhibition target of peroxynitrite is on the PSII acceptor side. In the presence of the herbicide DCMU, the chlorophyll (Chl) a fluorescence induction curve is inhibited by peroxynitrite, but the slow phase of the Chl a fluorescence decay does not change. EPR studies demonstrate that the Signal II slow and Signal II fast of peroxynitrite-treated Tris-washed PSII membranes are induced at room temperature, implying that the redox active tyrosines Y Z and Y D of PSII are not significantly nitrated. A featureless EPR signal with a g value of approximately 2.0043 ± 0.0003 and a line width of 10 ± 1 G is induced under continuous illumination in the presence of peroxynitrite. This new EPR signal corresponds with the semireduced plastoquinone Q A in the absence of magnetic interaction with the non-heme Fe 2+ . We conclude that peroxynitrite impairs PSII electron transport in the Q A Fe 2+ niche. |
| Databáze: | OpenAIRE |
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