Dark production of reactive oxygen species in photosystem II membrane particles at elevated temperature: EPR spin-trapping study
Jazyk angličtina Země Nizozemsko Médium print-electronic
Typ dokumentu časopisecké články, práce podpořená grantem
PubMed
17395149
DOI
10.1016/j.bbabio.2007.02.011
PII: S0005-2728(07)00044-8
Knihovny.cz E-zdroje
- MeSH
- elektronová paramagnetická rezonance metody MeSH
- fotosystém II (proteinový komplex) chemie metabolismus MeSH
- intracelulární membrány metabolismus MeSH
- reaktivní formy kyslíku metabolismus MeSH
- spin trapping metody MeSH
- teplota * MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- fotosystém II (proteinový komplex) MeSH
- reaktivní formy kyslíku MeSH
In our study, EPR spin-trapping technique was employed to study dark production of two reactive oxygen species, hydroxyl radicals (OH.) and singlet oxygen ((1)O2), in spinach photosystem II (PSII) membrane particles exposed to elevated temperature (47 degrees C). Production of OH., evaluated as EMPO-OH adduct EPR signal, was suppressed by the enzymatic removal of hydrogen peroxide and by the addition of iron chelator desferal, whereas externally added hydrogen peroxide enhanced OH. production. These observations reveal that OH. is presumably produced by metal-mediated reduction of hydrogen peroxide in a Fenton-type reaction. Increase in pH above physiological values significantly stimulated the formation of OH., whereas the presence of chloride and calcium ions had the opposite effect. Based on our results it is proposed that the formation of OH. is linked to the thermal disassembly of water-splitting manganese complex on PSII donor side. Singlet oxygen production, followed as the formation of nitroxyl radical TEMPO, was not affected by OH. scavengers. This finding indicates that the production of these two species was independent and that the production of (1)O2 is not closely linked to PSII donor side.
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