Singlet oxygen (1O2) is formed by triplet-triplet energy transfer from triplet chlorophyll to O2 via Type II photosensitization reaction in photosystem II (PSII). Formation of triplet chlorophyll is associated with the change in spin state of the excited electron and recombination of triplet radical pair in the PSII antenna complex and reaction center, respectively. Here, we have provided evidence for the formation of 1O2 by decomposition of protein hydroperoxide in PSII membranes deprived of Mn4O5Ca complex. Protein hydroperoxide is formed by protein oxidation initiated by highly oxidizing chlorophyll cation radical and hydroxyl radical formed by Type I photosensitization reaction. Under highly oxidizing conditions, protein hydroperoxide is oxidized to protein peroxyl radical which either cyclizes to dioxetane or recombines with another protein peroxyl radical to tetroxide. These highly unstable intermediates decompose to triplet carbonyls which transfer energy to O2 forming 1O2. Data presented in this study show for the first time that 1O2 is formed by decomposition of protein hydroperoxide in PSII membranes deprived of Mn4O5Ca complex.

• MeSH
• chlorofyl metabolismus   MeSH
• elektronová paramagnetická rezonance metody   MeSH
• fotosystém II (proteinový komplex) metabolismus   MeSH
• kyslík metabolismus   MeSH
• oxidace-redukce MeSH
• peroxid vodíku metabolismus   MeSH
• peroxidy metabolismus   MeSH
• přenos energie fyziologie   MeSH
• singletový kyslík metabolismus   MeSH
• světlo MeSH
• světlosběrné proteinové komplexy metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH