FUNCTION OF HELIOBACTERIA- AND GREEN SULFUR BACTERIA-TYPE REACTION CENTERS

日光细菌和绿硫细菌型反应中心的功能

• 批准号: 10044218
• 负责人: SAKURAI Hidehiro
• 金额: $ 4.93万
• 依托单位: Waseda University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B).
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10044218/
• 关键词: Green Sulfur Bacteria; Heliobacteria; Reaction Center; Iron-Sulfur Cluster; Cytochrome; Quinone; Electron Transfer; Photosynthesis; 反応中心; 閃光分光; フェレドキシン; 電子伝達

In the reaction center complex (PS-C) from the green sulfur bacterium Chlorobium tepidum, A_0 and three Fe-S clusters function on the accepter side of the electron transfer chain and two molecules of cyt c-551 on the donor side. From multiple-flash-induced spectroscopy, we could not find any possibilities of functioning of quinone in the main electron transfer chain. On the donor side, the reduction rate of P840^+ after the first flash differed from that after the second flash, which was adequately explained by a functionally equivalent two cyt c-551 model. From the difference spectra of PS-C after the 1^<st>, 2^<nd> and the 3^<rd> flash, functioning of three Fe-S clusters was confirmed, corroborating the non-involvement of quinines on the acceptor side in the electron transfer chain, From the rereduction rates of P840^+, the rates of charge recombination between P840^+ and three Fe-S clusters and those of the leak of electron to the reaction mdeium were estimated. Analyses of the results indicate that the E_0 value of the most exposed Fe-S cluster is not the highest among the three. Four ferredoxins (Fd) were purified from C.tepidum. All of these Fd supported very high rate of NADP^+ photoreduction in the presence of PS-C from C.repidum and FNR from spinach, although their affinities differ each other.RC (PS-H) from Heliobacillus mobilis was solubilized with a detergent, and partially purified by sucrosedensity centrifugation, and by chromatography. The PS-H preparation contained several polypeptides, showed a low Fd-reducing activity, and was sensitive to oxygen. Two Fd were purified from the bacterium. One of them had high affinity with PS-C and the other low affinity.

在绿色硫细菌Chlorobium tepidum的反应中心复合物（PS-C）中，A_0和三个Fe-S簇在电子传递链的受体侧起作用，两个cyt c-551分子在供体侧起作用。从多次闪光诱导光谱，我们不能找到任何可能性的功能醌的主要电子转移链。在供体侧，第一次闪光后P840^+的还原速率与第二次闪光后不同，这可以通过功能等效的两个cyt c-551模型充分解释。从PS-C在1^<st>、2^<nd>和3^<rd>闪光后的差谱图中，证实了三个Fe-S团簇的作用，证实了奎宁在电子转移链的受体侧不参与。从P840^+的再还原速率，估算了P840^+与三个Fe-S团簇之间的电荷复合速率和电子向反应介质的泄漏速率。结果表明，暴露量最大的Fe-S团簇的E_0值并不是最高的。从C. tepidum中纯化了四种铁氧化还原蛋白（Fd）。所有这些Fd都支持在来自C.repidum的PS-C和来自菠菜的FNR存在下非常高的NADP^+光还原速率，尽管它们的亲和力彼此不同。来自运动太阳杆菌的RC（PS-H）用去污剂溶解，并通过蔗糖密度离心和色谱法部分纯化。PS-H制剂含有几种多肽，表现出低的Fd还原活性，并且对氧敏感。从该菌中纯化出两个Fd。其中一个与PS-C的亲和力较高，另一个亲和力较低。

项目成果

Seo, D.et al.: "Purifications of ferredoxins and their reaction with purified reaction center complex from the green sulfur bacterium Chlorobium tepidum"Biochimica biophysica Acta. 1503. 377-384 (2001)

Seo, D. 等人：“铁氧还蛋白的纯化及其与来自绿色硫细菌温热绿菌的纯化反应中心复合物的反应”Biochimica biophysicala Acta。