Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, Moscow, 119234, Russia.
J Plant Res. 2024 Nov;137(6):1189-1200. doi: 10.1007/s10265-024-01584-7. Epub 2024 Oct 2.
In the region of slightly acidic pH (рН 5.7), the manganese cluster in oxygen-evolving complex of photosystem II (PSII) is more resistant to exogenous reductants. The effect of such pH on the heat inactivation efficiency of the electron transport chain (O evolution and 2,6-dichlorophenolindophenol reduction) in PSII membranes and thylakoid membranes was investigated. Under thylakoid membranes illumination accompanied by lumen acidification, their resistance to heat inactivation increases. In the presence of protonophores, the rate of heat inactivation increases, which seems to be associated not with the protonophore mechanism, but with structural and/or functional changes in membranes. In PSII membrane preparations, the efficiency of the oxygen evolution inhibition at pH 5.7 is also lower than at pH 6.5. The role of reactive oxygen species in thermal inactivation of photosynthetic membranes was investigated using a lipophilic cyclic hydroxylamine ESR spin probe.
在略酸性 pH 值（рН 5.7）条件下，光合作用系统 II （PSII）中氧气释放复合物中的锰簇对外加还原剂具有更强的抗性。研究了这种 pH 值对 PSII 膜和类囊体膜中电子传递链（O 释放和 2,6-二氯酚靛酚还原）热失活效率的影响。在类囊体膜光照伴随腔室酸化的情况下，它们对热失活的抵抗力增加。在质子载体存在下，热失活的速度增加，这似乎与质子载体机制无关，而是与膜的结构和/或功能变化有关。在 PSII 膜制剂中，在 pH 5.7 时氧气释放的抑制效率也低于 pH 6.5。使用亲脂性环状羟胺 ESR 自旋探针研究了活性氧物质在光合作用膜热失活中的作用。
