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Specific degradation of the D1 protein in photosystem II

光系统 II 中 D1 蛋白的特异性降解

基本信息

批准号：
09640783
负责人：
ONO Taka-aki
金额：
$ 1.86万
依托单位：
The Institute of Physical and Chemical Research (RIKEN)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

1) Various types of derivatives of phloroglucinol were synthesized in order to investigate the structure/function relationship on the D1 protein breakage activity. For the activity, OH-group at positions 2,4,6 on phenol ring is essential. Derivatives without a bulky hydrophobic side chain at position 3 showed very weak activity, indicating that the bulky group is also required for the activity. A derivative (G63) that has not nitro group at position 3 but has substituted group at position 6 has a unique activity that breaks the D1 protein to produce the same fragments as those found by photoinhibitory illumination. 2) Illumination of Ca-depleted PS II membranes sample retaining an abnormal S_2-state generated two EPR signals at g =2 region. One signal was ascribed to dipole interaction between a radical pair, and the other signal was ascribed to interaction between a radical and the Mn-cluster. A new high-spin EPR signal was detected when the latter signal was produced. 3) Spin-exchange structures of the S_2-state Mn-cluster were numerically evaluated. The calculation was performed by taking into account the magnetic properties of the S_2 multiline signal and the effective hyperfine constants determined by simulating oriented multiline spectrum. 4) Binding of Mn^<2+> to Mn-depleted PS II and electron donation from the bound Mn^<2+> to an oxidized Y_Z tyrosine were studied, and found that Mn-depleted membranes have only one unique binding site which has high affinity and high specificity for Mn^<2+>, and that Mn^<2+> bound to this site can be deliver an electron to Y_Z^+ with high efficiency.

1)为了研究间苯三酚衍生物对D1蛋白断裂活性的构效关系，合成了不同类型的间苯三酚衍生物。酚环上2、4、6位的OH基团对活性是必不可少的。在位置3处没有大体积疏水侧链的衍生物显示出非常弱的活性，表明大体积基团也是活性所需的。在3位不具有硝基但在6位具有取代基的衍生物（G63）具有独特的活性，其断裂D1蛋白质以产生与通过光抑制照明发现的片段相同的片段。2)光照保留异常S_2态的贫Ca PS II膜样品，在g =2区域产生两个EPR信号。一个信号归因于自由基对之间的偶极相互作用，另一个信号归因于自由基和Mn簇之间的相互作用。当后者的信号产生时，检测到一个新的高自旋EPR信号。3)计算了Mn团簇S_2态的自旋交换结构。计算中考虑了S_2多线信号的磁特性和由模拟定向多线谱确定的有效超精细常数。4)研究了Mn^<2+>与贫Mn PS Ⅱ的结合以及Mn^<2+与氧化Y_Z酪氨酸的电子传递，发现贫Mn膜只有一个对Mn^<2+具有高亲和力和高特异性的结合位点，结合在该位点上的Mn^<2+>能高效地将电子传递给Y_Z^<2+。