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Mitochondrial Phosphorylating Supercomplex Reveals Peculiar Features in Water Specific Point 20 Cтезисы доклада
- Авторы: Skorobogatova Y.A., Nesterov S.V., Yaguzhinsky L.S.
- Сборник: Structure and Functions of Biomembranes 2014, MIPT
- Серия: Book of Abstracts
- Тезисы
- Год издания: 2014
- Место издания: Dolgoprudny
- Первая страница: 152
- Последняя страница: 153
- Аннотация: In [1] it has been shown that under hypotonic condition (medium osmolarity 120 mosM) at room temperatures (15-22 °C) osmotic pressure rearranges mitochondrial OxPhos system and makes it operate as complete supercomplex, including electron- transport chain proteins and ATP-syntetase complex. A purpose of present work was to investigate whether such conditions give OxPhos system any advantages, for example some energy gain. Measuring parameter ADP/O (which shows an efficiency of phosphorylation) in wide temperature range, we found two temperature regions where ADP/O is maximal and close to theoretical value. (Fig.1) One of them is the range of physiological temperatures 30-40 °C. Unexpectedly another range proved to be very narrow (not wider than 1 °C) vicinity of 19 °C. We found out that ADP/O at 19 °C rises abruptly up to the theoretical level of 2, while at neighbouring temperatures ADP/O is about 1,5. General reduction of ADP/O level at room temperatures is shown to be caused by uncoupling effect of endogenous fatty acids. They are endogenous substrates of mitochondrial oxidation. To reproduce physiological conditions, we deliberately have not removed them from membranes during mitochondrial isolation. The special temperature 19 °C is characterized by stronger immunity of OxPhos system to uncoupling effect of fatty acids. If fatty acids are removed from membranes, the system is able to operate with maximal efficiency at all room temperatures. That immunity is so strong that even when exogenous fatty acids are added up to almost complete uncoupling, ADP/O at 19 °C in comparison with neighboring temperatures is steel significantly rised. The special temperature observed suddenly coincides with narrow temperature gap where temperature-dependent structural rearrangement of mitochondrial membrane has been detected in [2] under the same conditions. Stronger aggregation of membrane proteins has been found at 19±2 °C by measuring tryptophan fluorescence quenching by pyrene localised in lipid membrane component. (Fig.2) Thus, near 19 °C OxPhos system operating as supercomplex displays structural and functional special features. It is protected (partially or fully) from mild uncoupling. The anomalous narrowness of temperature gap where both effects are observed is of great question. Special state of OxPhos system under conditions of osmotic pressure in immediate vicinity of 19 °C could be regarded as intermediate state of supercomplex as highly organized structure. It is worth to notice that 19 °C is also the special temperature for water (e.g. there is OH-bond energy anomaly at this temperature [3]). So one could link the effects discussed with melting of highly organized proteins hydration shell.
- Добавил в систему: Ягужинский Лев Сергеевич