在光系统 II 的放氧反应中是否有直接的氯离子辅因子需求？
Is there a direct chloride cofactor requirement in the oxygen-evolving reactions of photosystem II?
机构信息
Max-Volmer-Institut, Technische Universität Berlin, Straße des 17. Juni 135, 1000, Berlin 12, FRG.
出版信息
Photosynth Res. 1990 Jul;25(1):59-72. doi: 10.1007/BF00051736.
The dark incubation at room temperature of photosystem II (PS II) membrane fragments in a chloride-free medium at pH 6.3 slowly leads to large chloride-restorable and non-restorable O2 evolution activity losses with time as compared with control samples incubated in the presence of 10 mM NaCl. The chloride requirement in O2 evolution generated under these conditions reveals a complex interplay among various experimental parameters, including the source of the plant material, the times of incubation, the sample concentration, the chloride concentration, as well as those treatments which are believed to specifically displace chloride from PS II such as alkaline pH pretreatment and Na2SO4 addition. The results indicate that secondary, structural changes within the PS II complex are an important factor in determining the influence of chloride on the O2 evolution activity and raise the question whether or not chloride ions actually play a direct cofactor role in the water-oxidizing reactions leading to O2 evolution.
在 pH 值为 6.3 的无氯介质中，室温下对光系统 II（PS II）膜片段进行暗孵育，与在存在 10 mM NaCl 的情况下孵育的对照样品相比，随着时间的推移，会导致大量可还原和不可还原的氯的 O2 释放活性损失。在这些条件下产生的 O2 释放所需的氯揭示了各种实验参数之间的复杂相互作用，包括植物材料的来源、孵育时间、样品浓度、氯浓度，以及那些被认为可以特异性置换 PS II 中的氯的处理方法，如碱性 pH 预处理和添加 Na2SO4。结果表明，PS II 复合物内的二级、结构变化是决定氯对 O2 释放活性影响的一个重要因素，并提出了一个问题，即氯离子是否实际上在导致 O2 释放的水氧化反应中发挥直接辅助因子的作用。
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