Institute of Basic Biological Problems, FRC PSCBR RAS, 142290 Pushchino, Russia.
Bionanotechnology Laboratory, Institute of Molecular Biology and Biotechnology, Azerbaijan National Academy of Sciences, AZ1073 Baku, Azerbaijan.
Cells. 2022 Aug 28;11(17):2680. doi: 10.3390/cells11172680.
The effects of the novel [CuL]Br complex (L = bis{4H-1,3,5-triazino [2,1-b]benzothiazole-2-amine,4-(2-imidazole)}copper(II) bromide complex) on the photosystem II (PSII) activity of PSII membranes isolated from spinach were studied. The absence of photosynthetic oxygen evolution by PSII membranes without artificial electron acceptors, but in the presence of [CuL]Br, has shown that it is not able to act as a PSII electron acceptor. In the presence of artificial electron acceptors, [CuL]Br inhibits photosynthetic oxygen evolution. [CuL]Br also suppresses the photoinduced changes of the PSII chlorophyll fluorescence yield (F) related to the photoreduction of the primary quinone electron acceptor, Q. The inhibition of both characteristic PSII reactions depends on [CuL]Br concentration. At all studied concentrations of [CuL]Br, the decrease in the F level occurs exclusively due to a decrease in Fv. [CuL]Br causes neither changes in the F level nor the retardation of the photoinduced rise in F, which characterizes the efficiency of the electron supply from the donor-side components to Q through the PSII reaction center (RC). Artificial electron donors (sodium ascorbate, DPC, Mn) do not cancel the inhibitory effect of [CuL]Br. The dependences of the inhibitory efficiency of the studied reactions of PSII on [CuL]Br complex concentration practically coincide. The inhibition constant Ki is about 16 µM, and logKi is 4.8. As [CuL]Br does not change the aromatic amino acids' intrinsic fluorescence of the PSII protein components, it can be proposed that [CuL]Br has no significant effect on the native state of PSII proteins. The results obtained in the present study are compared to the literature data concerning the inhibitory effects of PSII Cu(II) aqua ions and Cu(II)-organic complexes.
新型 [CuL]Br 配合物（L = 双{4H-1,3,5-三嗪并[2,1-b]苯并噻唑-2-胺,4-(2-咪唑)}铜(II)溴配合物）对菠菜分离的 PSII 膜的光系统 II（PSII）活性的影响进行了研究。在没有人工电子受体的情况下，PSII 膜不能进行光合作用产氧，但在 [CuL]Br 的存在下，表明它不能作为 PSII 电子受体。在人工电子受体存在的情况下，[CuL]Br 抑制光合作用产氧。[CuL]Br 还抑制与初级醌电子受体 Q 的光还原相关的 PSII 叶绿素荧光产额（F）的光诱导变化。两种特征 PSII 反应的抑制均取决于 [CuL]Br 浓度。在所有研究的 [CuL]Br 浓度下，F 值的降低仅归因于 Fv 的降低。[CuL]Br 既不会引起 F 值的变化，也不会延迟 F 的光诱导升高，这表征了电子从供体侧组件通过 PSII 反应中心（RC）向 Q 的供应效率。人工电子供体（抗坏血酸钠、DPC、Mn）不能取消 [CuL]Br 的抑制作用。研究的 PSII 反应的抑制效率与 [CuL]Br 配合物浓度的依赖性实际上是一致的。抑制常数 Ki 约为 16 µM，logKi 为 4.8。由于 [CuL]Br 不会改变 PSII 蛋白组分的芳香族氨基酸固有荧光，因此可以提出 [CuL]Br 对 PSII 蛋白的天然状态没有显著影响。本研究获得的结果与有关 PSII Cu(II) 水合离子和 Cu(II)-有机配合物抑制作用的文献数据进行了比较。
