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首页> 外文期刊>Biochemistry >SECONDARY ELECTRON TRANSFER PROCESSES IN MEMBRANES OF HELIOBACILLUS MOBILIS
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SECONDARY ELECTRON TRANSFER PROCESSES IN MEMBRANES OF HELIOBACILLUS MOBILIS

机译：嗜肝球菌膜的二次电子转移过程

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Picosecond transient absorption difference spectroscopic experiments were performed on membranes of the antenna/reaction center complex of Heliobacillus mobilis to study the electron transfer processes. Particular emphasis was placed on the blue spectral region, where the difference spectra of iron-sulfur centers and quinones are significantly different. Spectra were measured at room temperature in the wavelength region from 400 to 470 nm and from 630 to 730 nm. Laser excitation was into the 788 nm Q(y) band of the bacteriochlorophyll g of the reaction center complex. Global analysis in both wavelength regions reveals three kinetic components. A 25 ps phase originates from the decay of the excited state of antenna to form the primary charge-separated state P798(+)A(0)(-); a 600 ps component is assigned to the electron transfer from the primary electron acceptor A(0) to a secondary electron acceptor; a nondecaying component on the time scale measured represents the formation of the secondary charge-separated state. When the secondary electron accepters were reduced by adding dithionite at pH 11, the 600 ps component disappeared. Only a 25 ps component and a constant were observed in the 630-730 nm region. The 25 ps component is assigned to the excitation decay in the antenna and the formation of P798(+)A(0)(-), just as in the nonreduced sample. In the reduced sample, the P798(+)A(0)(-) state does not decay on the time scale measured. In the 400-470 nm region, the same kinetic behavior was observed. The absorption difference spectra of the primary and the secondary electron acceptor were constructed from different charge-separated states. The A(0)(-) - A(0) spectrum resembles the spectrum of the same state from photosystem I, which also contains a Chl alpha molecule as the primary electron acceptor. The secondary electron acceptor X has an X(-) - X difference spectrum similar to F-x in photosystem I from higher plants. The spectra do not give any evidence in favor of a quinone acceptor in heliobacteria, although they do not rule out the possibility that such an acceptor is present.
机译：在运动发酵单胞菌的天线/反应中心复合物的膜上进行了皮秒瞬态吸收差光谱实验，以研究电子转移过程。特别强调的是蓝色光谱区域，其中铁硫中心和醌的光谱差异很大。在室温下在400至470nm和630至730nm的波长范围内测量光谱。激光激发进入反应中心复合物细菌叶绿素g的788 nm Q（y）带。在两个波长区域的全局分析揭示了三个动力学成分。 25 ps的相位源自天线的激发态的衰减，从而形成初级电荷分离态P798（+）A（0）（-）; 600 ps的分量被分配给从一次电子受体A（0）到二次电子受体的电子转移;在所测量的时间尺度上的非衰减成分表示二次电荷分离状态的形成。当通过添加pH 11的连二亚硫酸盐还原次级电子受体时，600 ps的成分消失了。在630-730 nm区域仅观察到25 ps的分量和常数。 25 ps分量被分配给天线中的激励衰减和P798（+）A（0）（-）的形成，就像在非缩减样本中一样。在精简样本中，P798（+）A（0）（-）状态不会在所测量的时间尺度上衰减。在400-470nm区域，观察到相同的动力学行为。初级和次级电子受体的吸收差谱由不同的电荷分离态构成。 A（0）（-）-A（0）光谱类似于来自光系统I的相同状态的光谱，该系统还包含一个Chl alpha分子作为主要电子受体。次级电子受体X的X（-）-X差异光谱类似于高等植物的光系统I中的F-x。尽管不排除这种受体存在的可能性，但光谱并未提供任何证据支持在嗜细菌细菌中使用醌受体。

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