Nanosecond fluorescence from isolated photosynthetic reaction centers of Rhodopseudomonas sphaeroides.
Nanosecond fluorescence from isolated photosynthetic reaction centers of Rhodopseudomonas sphaeroides.
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来自球形红假单胞菌的分离光合反应中心的纳秒荧光。
DOI：
10.1016/0005-2728(84)90205-6
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发表时间：
1984
期刊：
影响因子：
--
通讯作者：
Parson,WW
中科院分区：
文献类型：
--
作者：
Woodbury,NW;Parson,WW
使用单光子计数技术测量从球形红假单胞菌分离的反应中心的荧光的时间过程。当电子转移因受电子醌的还原而受阻时，由于逆反应从瞬态自由基对状态 PF 再生激发态 (P*)，反应中心会表现出相对较长寿命（延迟）的荧光。延迟荧光可分解为三个分量，在 295 K 时寿命分别为 0.7、3.2 和 11 ns。最慢的分量衰减时间常数与 PF 引起的吸光度变化相同，并且与吸光度变化相同，它取决于温度和磁场。延迟荧光的两个较快分量的时间常数基本上与温度和磁场无关。荧光还包括非常快（迅速）的成分，其振幅与从未还原的反应中心获得的荧光相似。瞬时荧光大概主要是在初始电荷转移反应从 P* 产生 PF 之前的时期发射的。根据瞬时荧光和延迟荧光的振幅，我们计算出 P* 和 PF 之间的初始标准自由能差在 295 K 时约为 0.16 eV，在 80 K 时约为 0.05 eV，这在一定程度上取决于溶剂的性质。延迟荧光的多相衰减被解释为 PF 自由能随时间的弛豫，在 295 K 时总共约为 0.05 eV，可能是由电子载体或蛋白质中的核运动引起的。
The time-course of fluorescence from reaction centers isolated fromRhodopseudomonas sphaeroideswas measured using single-photon counting techniques. When electron transfer is blocked by the reduction of the electron-accepting quinones, reaction centers exhibit a relatively long-lived (delayed) fluorescence due to back reactions that regenerate the excited state (P*) from the transient radical-pair state, PF. The delayed fluorescence can be resolved into three components, with lifetimes of 0.7, 3.2 and 11 ns at 295 K. The slowest component decays with the same time-constant as the absorbance changes due to PF, and it depends on both temperature and magnetic fields in the same way that the absorbance changes do. The time-constants for the two faster components of delayed fluorescence are essentially independent of temperature and magnetic fields. The fluorescence also includes a very fast (prompt) component that is similar in amplitude to that obtained from unreduced reaction centers. The prompt fluorescence presumably is emitted mainly during the period before the initial charge-transfer reaction creates PFfrom P*. From the amplitudes of the prompt and delayed fluorescence, we calculate an initial standard free-energy difference between P* and PFof about 0.16 eV at 295 K, and 0.05 eV at 80 K, depending somewhat on the properties of the solvent. The multiphasic decay of the delayed fluorescence is interpreted in terms of relaxations in the free energy of PFwith time, totalling about 0.05 eV at 295 K, possibly resulting from nuclear movements in the electron-carriers or the protein.