Centre de recherche en photobiophysique, Université du Québec à Trois-Rivières, C.P. 500, G9A 5H7, Trois-Rivières, (Québec), Canada.
Photosynth Res. 1991 Dec;30(2-3):123-30. doi: 10.1007/BF00042010.
The inhibitory effect of Zn(2+) on photosynthetic electron transport was investigated in native and CaCl2-treated (depleted in extrinsic polypeptides) Photosystem II (PS II) submembrane preparations. Inhibition of 2,6-dichlorophenolindophenol photoreduction by Zn(2+) was much stronger in protein-depleted preparations in comparison to the native form. It was found that Ca(2+) significantly reduced the inhibition in the native PS II preparations, as did Mn(2+) in a combination with H2O2 in the protein-depleted counterparts. No other tested monovalent or divalent cations could replace Ca(2+) or Mn(2+) in the respective experiments. Diphenylcarbazide could partially relieve (40-45%) the inhibition in both types of preparations. The above indicates the presence of an active Zn(2+) inhibitory site on the donor side of PS II. However, neither Ca(2+) nor Mn(2+) could completely prevent inhibition by high concentrations of Zn(2+) (>1 mM). We propose that elevated levels of Zn(2+) strongly perturb the conformation of the PS II core complex and might also affect the acceptor side of the photosystem.
研究了 Zn(2+) 对天然态和 CaCl2 处理（除去外向多肽）的 PS II 亚膜制剂中光合电子传递的抑制作用。与天然态相比，Zn(2+) 对 2,6-二氯苯酚靛酚光还原的抑制作用在蛋白缺失制剂中要强得多。结果发现，Ca(2+) 显著降低了天然 PS II 制剂的抑制作用，Mn(2+) 与 H2O2 结合在蛋白缺失的对应物中也有同样的作用。在各自的实验中，没有其他测试的一价或二价阳离子可以替代 Ca(2+) 或 Mn(2+)。二苯卡巴肼可部分缓解（40-45%）两种类型制剂的抑制作用。这表明 PS II 的供体侧存在一个活跃的 Zn(2+) 抑制位点。然而，高浓度的 Zn(2+)（>1mM）既不能完全阻止 Ca(2+) 也不能完全阻止 Mn(2+) 的抑制作用。我们提出，Zn(2+) 水平的升高强烈扰乱 PS II 核心复合物的构象，也可能影响光系统的受体侧。
