Electrogenic steps in the redox reactions catalyzed by photosynthetic reaction-centre complex from Rhodopseudomonas viridis.
Electrogenic steps in the redox reactions catalyzed by photosynthetic reaction-centre complex from Rhodopseudomonas viridis.
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由绿色红假单胞菌的光合反应中心复合物催化的氧化还原反应中的生电步骤。
DOI：
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
S. Zaberezhnaya
中科院分区：
文献类型：
--
作者：
S. Dracheva;L. Drachev;Alexander A. Konstantinov;A. Semenov;V. Skulachev;A. M. Arutjunjan;V. A. Shuvalov;S. Zaberezhnaya
本文研究了草绿红球藻反应中心络合物的产电和氧化还原过程。与以前的观点相反，它表明，紧密结合的细胞色素c的所有四个血红素具有不同的Em值（-60，+20，+310和+380 mV）。前三个血红素分别在554 nm、552 nm和556 nm处显示α吸收最大值。380-mV血红素显示分裂α带，最大值在559 nm处，肩部在552 nm处。这种分裂是由于铁卟啉环中的非简并Qx和Qy跃迁，如磁性圆二色光谱所示。快速动力学测量表明，在氧化还原电位下，当只有高电位血红素c-559和c-556被还原时，血红素c-559似乎是P-960+的电子供体（τ = 0.32微秒），而血红素c-556用于再还原c-559（τ = 2.5微秒）。在第三个血红素（c-552）的还原，P-960+还原率增加两倍（τ = 0.17微秒）和所有光诱导的氧化还原事件内的细胞色素似乎是在闪光后不到1微秒完成。初步推测氧化还原中心的排列顺序为：c-554，c-556，c-552，c-559，P-960。为了研究产电作用，Rps的反应中心复合物。viridis被纳入asolectin脂质体，和快速动力学的激光闪光诱导的电势差已被测量在吸附在磷脂浸渍膜的蛋白脂质体。发现由单个15 ns闪光引起的电差异高达100 mV。已发现光电响应涉及四个产电阶段，与（I）P-960还原QA;（II）血红素c-559还原P-960+;（III）c-556还原c-559和（IV）Q2-B质子化有关。阶段I，II，III和IV的相对贡献被认为是等于70%，15%，5%和10%，分别为整个产电过程。同时，从Deisenhofer等人[J. Mol. Biol. 180，385-398（1984）]中所描述的方法，分别为22%、18.5%和26%。这表明产电相的效率首先取决于各个膜区域的介电常数的值，而不是取决于所涉及的氧化还原基团之间的距离。（400字处截断摘要）
Electrogenic and redox events in the reaction-centre complexes from Rhodopseudomonas viridis have been studied. In contrast to the previous points of view it is shown that all the four hemes of the tightly bound cytochrome c have different Em values (-60, +20, +310 and +380 mV). The first three hemes reveal alpha absorption maxima at 554 nm, 552 nm and 556 nm respectively. The 380-mV heme displays a split alpha band with a maximum at 559 nm and a shoulder at 552 nm. Such a splitting is due to non-degenerated Qx and Qy transitions in the iron-porphyrin ring as demonstrated by magnetic circular dichroism spectra. Fast kinetic measurements show that, at redox potentials when only high-potential hemes c-559 and c-556 are reduced, heme c-559 appears to be the electron donor to P-960+ (tau = 0.32 microsecond) whereas heme c-556 serves to rereduce c-559 (tau = 2.5 microsecond). Upon reduction of the third heme (c-552), the P-960+ reduction rate increases twofold (tau = 0.17 microsecond) and all photoinduced redox events within the cytochrome appear to be complete in less than 1 microsecond after the flash. The following sequence of the redox centers is tentatively suggested: c-554, c-556, c-552, c-559, P-960. To study electrogenesis, the reaction-centre complexes from Rps. viridis were incorporated into asolectin liposomes, and fast kinetics of laser flash-induced electric potential difference has been measured in proteoliposomes adsorbed on a phospholipid-impregnated film. The electrical difference induced by a single 15-ns flash was found to be as high as 100 mV. The photoelectric response has been found to involve four electrogenic stages associated with (I) QA reduction by P-960; (II) reduction of P-960+ by heme c-559; (III) reduction of c-559 by c-556 and (IV) protonation of Q2-B. The relative contributions of stages I, II, III and IV are found to be equal to 70%, 15%, 5% and 10%, respectively, of the overall electrogenic process. At the same time, the first three respective distances along the axis normal to the membrane plane covered by electrons, calculated from X-ray data of Deisenhofer et al. [J. Mol. Biol. 180, 385-398 (1984)], are 22%, 18.5% and 26%. This indicates that the efficiency of electrogenic phases depends first of all upon the value of the dielectric constant of the respective membrane regions rather than upon the distance between the redox groups involved.(ABSTRACT TRUNCATED AT 400 WORDS)
施加的电场对平面脂质双层中重构的反应中心的电荷复合动力学的影响。
影响因子：
3.4
作者：
Gopher,A;Blatt,Y;Schönfeld,M;Okamura,MY;Feher,G;Montal,M
通讯作者：
Montal,M
绿色红假单胞菌反应中心的主要供体回收动力学。
DOI：
10.1016/0005-2728(86)90212-4
发表时间：
1986
期刊：
Biochimica et biophysica acta
影响因子：
--
作者：
Shopes,RJ;Wraight,CA
通讯作者：
Wraight,CA