Antenna size dependence of fluorescence decay in the core antenna of photosystem I: estimates of charge separation and energy transfer rates.
Antenna size dependence of fluorescence decay in the core antenna of photosystem I: estimates of charge separation and energy transfer rates.
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光系统 I 核心天线中荧光衰减的天线尺寸依赖性：电荷分离和能量转移速率的估计。
DOI：
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发表时间：
1987
影响因子：
11.1
通讯作者：
G. Fleming
中科院分区：
文献类型：
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作者：
T. G. Owens;S. P. Webb;L. Mets;R. S. Alberte;G. Fleming
我们研究了光系统I中能量迁移和捕获的光物理学，通过研究作为天线尺寸的函数的核心天线叶绿素的荧光的光谱和时间特性。时间相关的单光子计数被用来确定在孤立的P700叶绿素a-蛋白复合物和在缺乏光系统II反应中心复合物的莱茵衣藻突变体的荧光寿命。在这两种类型的样品中的荧光衰减是由一个快速（15-45皮秒）的组件，这是由于在光系统I核心天线的激发寿命占主导地位。这些激发衰减主要是由一个有效的光化学猝灭P700。测得的寿命显示出线性关系的核心天线的大小。先前在用于光合色素阵列中的激发迁移和捕获的晶格模型中预测了激发寿命对天线尺寸的线性依赖性[Pearlstein，R.M. 04 The Story of the Woman（1982）光生物学35，835-844]。基于该模型，我们的数据预测光系统I反应中心光化学电荷分离的时间常数为2.8 +/- 0.7或3.4 +/- 0.7 psec，分别假设单体或二聚体P700。核心天线色素之间的激发转移的预测平均单步转移时间为0.21 +/- 0.04皮秒。在这些条件下，激发光系统I的迁移是接近扩散极限，与每个激发作出的平均2.4访问的反应中心之前，光转换。
We have examined the photophysics of energy migration and trapping in photosystem I by investigating the spectral and temporal properties of the fluorescence from the core antenna chlorophylls as a function of the antenna size. Time-correlated single photon counting was used to determine the fluorescence lifetimes in the isolated P700 chlorophyll a-protein complex and in a mutant of Chlamydomonas reinhardtii that lacks the photosystem II reaction center complex. The fluorescence decay in both types of sample is dominated by a fast (15-45 psec) component that is attributed to the lifetime of excitations in the photosystem I core antenna. These excitations decay primarily by an efficient photochemical quenching on P700. The measured lifetimes show a linear relationship to the core antenna size. A linear dependence of the excitation lifetime on antenna size was predicted previously in a lattice model for excitation migration and trapping in arrays of photosynthetic pigments [Pearlstein, R.M. (1982) Photochem. Photobiol. 35, 835-844]. Based on this model, our data predict a time constant for photochemical charge separation in the photosystem I reaction center of 2.8 +/- 0.7 or 3.4 +/- 0.7 psec, assuming monomeric or dimeric P700, respectively. The predicted average single-step transfer time for excitation transfer between core antenna pigments is 0.21 +/- 0.04 psec. Under these conditions, excitation migration in photosystem I is near the diffusion limit, with each excitation making an average of 2.4 visits to the reaction center before photoconversion.