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Quantitative assessment of the photosystem II oxygen-evolving complex inactivation by OJIP-curvesтезисы доклада
- Авторы: Tatiana Plyusnina, Sergey Khruschev, Natalia Degtereva, Elena Lovyagina, Elena Voronova, Elena Protasova, Boris Semin
- Сборник: 10th International Conference “Photosynthesis and Hydrogen Energy Research for Sustainability-2019", June 23 – 28, 2019, Saint Petersburg, Russia, Abstracts, ISBN 978-5-4386-1743-3
- Тезисы
- Год издания: 2019
- Место издания: Komarov Botanical Institute of the Russian Academy of Sciences St. Petersburg
- Первая страница: 71
- Последняя страница: 71
- Аннотация: To assess the activity of the photosystem II (PS II), fluorescence transients called OJIP-curves are traditionally used. The kinetics of chlorophyll a fluorescence is a multiphase curve. The phases of the curve are usually related to the stages of electron transfer in PS II. The initial part of the curve, the so-called K-phase, is usually related to the state of the oxygen-evolving complex (OEC) located on the donor side of PS II. To visualize the K-phase, a method of comparing induction curves based on subtracting control OJIP-curve from those recorded under different conditions is often used. It is believed that the appearance of the K-phase (maximum on the difference curve at about 300 μs) indicates the inactivation of the OEC in the sample. However, this method provides only a qualitative description of the OEC inactivation. We hypothesized that a change in the magnitude of the K-phase maximum (we called it as Δmax) may indicate a fraction of photosystems with inactivated OEC. Confirmation of this hypothesis would allow to quantify the degree of inactivation of OEC using OJIP-curves. To test this hypothesis, we conducted the following experiment to assess the degree of inactivation of OEC. We used photosystem II prepared from spinach leaves and cell suspension of Chlorella algae as model systems. At first, the samples were heated to a certain temperature in the range from 25°C to 50°C, then cooled, and the rate of oxygen evolution was measured, and fluorescence induction curves were recorded as well. The temperature dependences for the rate of oxygen evolution (VO2) and for the Δmax parameter, calculated from the induction curves, were obtained. The correlation coefficient between the temperature curves for VO2 and for Δmax measured on PS II samples was 0.99, whereas for Chlorella cells it was 0.95. The high correlation between the curves allows us to offer Δmax as a parameter that quantitatively characterizes the OEC inactivation degree.
- Добавил в систему: Хрущев Сергей Сергеевич