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Modification of Photosystem I reaction center by extraction-reconstitution of pigment cofactors

通过色素辅因子的提取-重构来修饰光系统 I 反应中心

基本信息

批准号：
11640656
负责人：
IKEGAMI Isamu
金额：
$ 0.9万
依托单位：
Teikyo University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

1. Most Chl α in the PsaA/B PSI complexes was removed without any loss of P700 by ether treatment, yielding the antenna-depleted PSI RC complexes that have a Chl α/P700 ratio of 12. On addition of Chl b with a phosphatidylglycerol, 9 - 14 Chl b per P700 bound to the Chl α - binding sites in the antenna-depleted complexes and the bound Chl b acted as antenna as efficiently as in situ Chl α.2. A femtosecond transient absorption spectroscopy of the PSI RC in which one (or more?) of the PSI electron-transport co factor (s) was extracted by the treatment of PSI complex with water-containing ether, showed that under the P700-neutral conditions and upon the 630 nm excitation, the ratio of the amount of the reduced Ao to that of the excited P700 decreased as the temperature goes down. At most 40 % of the RC can undergo the primary charge separation at 9 K, even though about 100 % PSI RC shows subpicosecond primary charge separation at a physiological temperature. The results suggest that a the … More rmal process is involved in the charge separation of the incomplete PSI RC.3. In order to try to construct Zn-Chl α instead of Mg-Chl, Chlorella cells were cultured at the high concentration of Zn^<2+>. Zn of more than 0.5 mmol/1 was lethal to Chlorella when grown autotrophically in the light. However, when grown heterotropphically in the dark, Chlorella had an ability to proliferate after long lag phase even in the presence of 67 mmol/1 of Zn. The Zn-inoculated cells showed the absorption spectrum of Chl with peaks at 415 and 670nm at the beginning of the growth. During the growth, there appeared a Chl form with a peak at 680 nm. Identification of the Chls in the Zn-inoculated cells is now in progress.4. The method for a selective degradation of P700 and A_o was established with spinach P700-enncned complexes that had a Chl α/P700 ratio of 10 by incubation in pH11.5 at 10 ℃. The degradation of P100 and A_o proceeded more rapid with making pH or temperature higher. The degradation stopped immediately, but did not recover, by backing pH to 8. The absorption peak of P700 temporarily shifted to 670 nm and then disappeared by this treatment. The reconstitution of P700 and/or A_o is now in progress with this preparation. Less

1. PsaA/B PSI复合物中的大部分Chl α通过醚处理被去除，而没有任何P700的损失，产生具有Chl α/P700比为12的触角耗尽的PSI RC复合物。在加入Chl B和磷脂酰甘油后，每个P700中有9 - 14个Chl B与触角缺失复合物中的Chl α结合位点结合，结合的Chl B与原位Chl α 2一样有效地充当触角。飞秒瞬态吸收光谱的PSI RC中，一个（或多个？）结果表明，在P700中性条件下，在630 nm激发下，随着温度的降低，P700的还原态Ao与激发态P700的比值减小。最多40%的RC可以在9 K下经历初级电荷分离，即使约100%的PSI RC在生理温度下显示亚皮秒初级电荷分离。结果表明， ...更多信息在不完全PSI RC的电荷分离中涉及到一个异常过程。为了尝试构建Zn-Chl α替代Mg-Chl，在高浓度Zn^<2+>下培养小球藻细胞。当锌浓度大于0.5mmol/l时，小球藻在光下自养生长时，锌对小球藻是致死的。然而，当在黑暗中异养生长时，即使在67 mmol/l的Zn的存在下，小球藻也能够在长滞后期后增殖。在生长初期，Zn接种的细胞在415和670 nm处有叶绿素的吸收峰。在生长过程中，出现了一个Chl型，在680 nm处有一个峰值。锌接种细胞中叶绿素的鉴定正在进行中。在pH11.5、10 ℃条件下，以叶绿素α/P700比值为10的菠菜P700-Encnc复合物为底物，建立了选择性降解P700和A_o的方法。pH值越高、温度越高，P100和AO的降解越快。降解立即停止，但通过将pH值恢复到8而没有恢复。P700的吸收峰暂时移动到670 nm，然后通过该处理消失。P700和/或A_o的重构现在正在用该制剂进行。少