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Peculiarities of Mn(II) Cation Oxidation in the Photosystem II without an Oxygen-Evolving Complex: Evolutionary Aspectстатья
- Авторы: Lovyagina E.R., Davletshina L.N., Semin B.K.
- Журнал: Moscow University Biological Sciences Bulletin
- Том: 77
- Номер: 2
- Год издания: 2022
- Издательство: Allerton Press
- Местоположение издательства: New York, N.Y., United States
- Первая страница: 92
- Последняя страница: 97
- DOI: 10.3103/S0096392522020055
- Аннотация: One of the main reactions in the process of light energy transformation in oxygenic organisms isthe extraction of electrons from water, which are necessary for the light stage of photosynthesis. The lightdependentoxidation of water is carried out by an oxygen-evolving complex (OEC), the catalytic center ofwhich is the cluster Mn4CaO5. OEC is located in photosystem II (PSII) on the lumen side of the thylakoidmembrane. The evolutionary origin of the PSII is unclear, as is the origin of the manganese cluster in theOEC. Recently, Johnson et al. (2013) suggested that, in the primary PSII in the Archean period, the clusterMn4CaO5 was absent, and PSII oxidized not water but Mn (II) cations, i.e., manganese cations were thesource of electrons. In the presented work, the authors investigated the possibility of the influence of someenvironmental factors (citrate and hydrogen peroxide) on the oxidation rate of Mn(II) cations by a PSII thatdoes not contain OEC. It was found that citrate inhibit the oxidation of Mn(II) cations binding them but doesnot extract Mn cations from OEC. Hydrogen peroxide, on the contrary, significantly increases the oxidationrate of manganese (from 28 ± 2 to 145 ± 7 μmol 2,6-dichlorophenolindophenol mg Chl–1 h–1 in the presenceof H2O2). Such effects should be taken into account when investigating the oxidation of manganese cationsby the photosystem as a possible source of electrons in the early stages of evolution.
- Добавил в систему: Ловягина Елена Рудольфовна