Identification of the tyrosyl residue as the secondary electron donor of Photosystem II reaction center.

鉴定酪氨酰残基作为光系统 II 反应中心的二次电子供体。

基本信息

批准号：
62540506
负责人：
TAKAHASHI Yuichiro
金额：
$ 1.09万
依托单位：
Okayama University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1987
资助国家：
日本
起止时间：
1987 至 1988
项目状态：
已结题

项目摘要

1.Identification of the subunit responsible for binding the electron donor of photosystem II by iodination experiment. The reduction kineties of EPR signal llslow in the prosence of iodido were measured with EPR spectroscopy and the amount of ^<125>I incroparated into the D2-protein in the reaction center of photosystem II was quantitated in a PS II core complex preparation. The amount of ^<125>I that was ineorporated into the D2-protein in the dark was correlated to the reduction of signal llslow by iodide. This correlation indicates that the site of iodide oxidation in the dark and the component giving rise to EPR signal llslow are located on the D2-protein in the PS II reaction center.2. Identification of tyrosyl residue functioning as the secondary electron donor, Z. The D1-protein is exclusively iodinated in the Photosystem II core complex as a result of photooxidation of iodide in the secondary electron donor, Z and then, was subjected to a peptide mapping analysis after partial … More clcavage at C-teminal side of methionine by CNDr. It was shown that a peptide fragment of about 3 kDa was exclusively iodinated and its N-terminal sequence indicated that it starts from Gly-128 and ends at Met-172. From the deduced sequence of D1, this fragment is supposed to contain two tyrosyl residues and it is coneluded that Tyr-161, which is located in the lumenal side of the thylakoid membrane, is iodinated and thus functions as the secondary electron donor, Z.3. Purification of photosystem II rcaction center polypeptides D1 and D2. Photosystem II reaction center polypeptides D1 and D2 ,which are hydrophobic and homologous, were purified on a large scale from photosystem II reaction center preparation by means of gel permeation HPLC in the presence of SDS. COOH-termini of the purified D1 and D2 were determined and were concluded to be Ala-344 and Leu-353, respectively. It is, therefore, shown that D1 loses 9 amino acid residues at C-terminus during maturation from a precursor from but that D2 is not processed. Less

1.识别亚基通过碘化实验结合光系统II的电子供体的识别。用EPR光谱法测量了iodido预测中EPR信号LSLOW的还原气体，并在PSS II核心复合物制备中定量 ^<125> I的量 ^<125> I递增到D2蛋白II中的D2-蛋白质。在黑暗中掺入D2-蛋白质的 ^<125> i的量与碘化物的降低信号llslow相关。这种相关性表明，在黑暗中的碘化物氧化位点，产生EPR信号LLSLOW的成分位于PS II反应中心的D2-蛋白上。2。鉴定酪酰居住在二级电子供体Z中。d1蛋白在光系统II核心复合物中仅碘化在二级电子供体中碘化的结果，Z，然后在甲基元素cn cn ddr cn ddr的cn-teminal side clcavage中进行肽映射分析。结果表明，大约3 kDa的肽片段仅被碘化，其N末端序列表明它从Gly-128开始，终止于Met-172。根据D1的推导序列，该片段有望包含两个酪酶保留，并且构造的是，位于类囊体膜的Lumenal侧的Tyr-161被碘化，因此是二级电子供体Z.3。光系统II rcaction Center多肽D1和D2的纯化。疏水且同源的光系统II反应中心多肽D1和D2在存在SDS的情况下通过凝胶渗透HPLC从光系统II反应中心制备大规模纯化。确定纯化的D1和D2的COOH末端，分别得出分别为ALA-344和LEU-353。因此，表明D1在从前体的成熟过程中丢失9个氨基酸在C末端保留，但该D2未加工。较少的