Studies on early events of photosynthetic electron transport---functions of Fe,Ca and M

光合电子传递早期事件的研究——Fe、Ca、M的功能

基本信息

批准号：
63440002
负责人：
KATOH Sakae
金额：
$ 1.22万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-63440002/
关键词：
Photosynthesis Electron transport Photosystem II Oxygen evolution Calcium Extrinsic 23 kDa protein NaCl treatment Iron 酸処理 23KDa蛋白質系1反応中心酸素発生反応 23kDaたんぱく質光化学系I 鉄イオウセンター

项目摘要

1. The number and function of Ca involved in photosystem II (PS II) electron transport were studied with oxygen evolving preparations isolated from rice and spinach. (1) PS II oxygen evolving membranes contained two Ca per PS II, which are heterogenous in binding affinity. A loosely bound Ca could be solubilized by detergent-treatments and the resulting PS II complexes containing only one Ca were highly active in oxygen evolution. Thus only one bound Ca is needed for PS II electron transport. (2) Treatment of PS II preparations with high concentrations of NaCl did not solubilize Ca, even though the treatment resulted in a strong inactivation of oxygen evolution and the lost activity was restored by added Ca. (3) A brief treatment at pH 3.0, which caused liberation of one out of the two Cabound to PS II membranes, failed to extract Ca from PS II complexes containing one Ca but induced Ca-reversible inactivation of oxygen evolution. This indicates that the acid-extractable Ca is not need … More ed for oxygen evolution. (4) The extrinsic 23 kDa protein was found to decrease the binding affinity of added Ca to pH 3.0- treated PS II preparations. (5) The above results are inconsistent with the view that NaCl- and pH 3.0-treatments inhibit oxygen evolution by extracting bound Ca and that the 23 kDa protein stabilizes or protects Ca in PS II preparation. Instead, detailed investigation on Ca concentration dependence of oxygen evolution in NaCl- and pH 3.0-treated preparations strongly suggest that the two treatments share a common mechanism of inactivation,i.e., a conformational change of the oxygen evolving complex.2. Crosslinking experiments showed that the extrinsic 33 kDa protein is located near the chlbinding 47 kDa protein and the association of the 33 kDa protein protects Mn against alkaline pH-treatment.3. Purified PS II reaction center complexes and D1-D2-cytochrome b559 complexes from the thermophilic cyanobacterium S. elongatus were found to contain one iron atom of unknown function in addition to a heme iron of cytochrome b559 and a non-heme iron locating near Q_A and Q_B. Less

1. 利用从稻米和菠菜中分离的析氧制剂研究了参与光系统 II (PS II) 电子传递的 Ca 的数量和功能 (1) PS II 析氧膜每个 PS II 含有两个 Ca，它们的结合是异质的。松散结合的 Ca 可以通过去垢剂处理而溶解，并且所得到的仅含有一种 Ca 的 PS II 复合物在析氧方面具有高活性，因此 PS II 电子传输只需要一种结合的 Ca 。准备工作高浓度的 NaCl 不会溶解 Ca，尽管该处理导致氧气释放的强烈失活，并且通过添加 Ca 恢复了失去的活性。 (3) 在 pH 3.0 下进行短暂处理，导致释放出其中的一种。两个 Ca 结合到 PS II 膜上，未能从含有一种 Ca 的 PS II 复合物中提取 Ca，但诱导了 Ca 可逆的析氧失活，这表明可酸提取的 Ca 不需要析氧 (4)。发现外源 23 kDa 蛋白会降低添加的 Ca 与 pH 3.0 处理的 PS II 制剂的结合亲和力 (5) 上述结果与 NaCl 和 pH 3.0 处理通过提取结合的 Ca 来抑制氧气释放的观点不一致。并且 23 kDa 蛋白稳定或保护 PS II 制剂中的 Ca 相反，对 NaCl 和 pH 3.0 处理的制剂中氧气释放的 Ca 浓度依赖性的详细研究强烈表明这两种处理。具有共同的失活机制，即放氧复合物的构象变化。交联实验表明，外在的 33 kDa 蛋白位于 Chl 结合 47 kDa 蛋白附近，并且 33 kDa 蛋白的结合可以保护 Mn 免受碱性 pH 的影响。 -处理.3.来自嗜热蓝细菌的纯化PS II反应中心复合物和D1-D2-细胞色素b559复合物除了细胞色素 b559 的血红素铁和位于 Q_A 和 Q_B Less 附近的非血红素铁之外，还发现 S. elongatus 还含有一个功能未知的铁原子。