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.通过碘化实验鉴定负责结合光系统II的电子供体的亚基。用EPR光谱测量了碘存在时EPR信号的还原动力学以及嵌入D2-中的^ 125 I的量。在PS II核心复合物制剂中对光系统II反应中心的蛋白质进行定量。掺入的^ 125 I的量。黑暗中的 D2 蛋白与碘化物对 llslow 信号的减少相关。这种相关性表明，黑暗中碘化物氧化的位点和产生 EPR 信号 llslow 的成分位于 PS II 中的 D2 蛋白上。 2. 鉴定作为次级电子供体 Z 的酪氨酰残基。由于光氧化作用，D1 蛋白在光系统 II 核心复合物中被完全碘化。 CNDr 在蛋氨酸的 C 末端部分裂解后，对第二电子供体 Z 中的碘化物进行肽图谱分析，结果显示约 3 kDa 的肽片段被完全碘化，其 N 被碘化。 -末端序列表明它从Gly-128开始，到Met-172结束。从D1的推导序列来看，该片段应该包含两个酪氨酰残基。结论是，位于类囊体膜的腔侧的Tyr-161被碘化，因此起到第二电子供体的作用，Z.3光系统II反应中心多肽D1和D2的纯化。 D1和D2是疏水性且同源的，在存在下通过凝胶渗透HPLC从光系统II反应中心制剂中大规模纯化。经SDS测定，纯化的D1和D2的COOH末端分别为Ala-344和Leu-353，因此表明D1在前体成熟过程中在C末端丢失了9个氨基酸残基。但 D2 未被处理。