Werst M, Jia Y, Mets L, Fleming G R
Department of Chemistry, University of Chicago, Illinois 60637.
Biophys J. 1992 Apr;61(4):868-78. doi: 10.1016/S0006-3495(92)81894-5.
The fluorescence decay kinetics of the photosystem I-only mutant strain of Chlamydomonas reinhardtii, A4d, are used to study energy transfer and structural organization in photosystem I (PSI). Time-resolved measurements over a wide temperature range (36-295 K) have been made both on cells containing approximately 65 core chl a/P700 and an additional 60-70 chl a + b from LHC proteins and on PSI particles containing 40-50 chl a/P700. In each case, the fluorescence decay kinetics is dominated by a short component, tau 1 which is largely attributed to the lifetime of the excitations in the core complex. The results are discussed in terms of simulations of the temperature dependence of tau 1 in model systems. Spectral inhomogeneity and the temperature dependence of the spectral lineshapes are included explicitly in the simulations. Various kinds of antenna arrangements are modeled with and without the inclusion of pigments with lower absorption energies than the trap (red pigments). We conclude that funnel arrangements are not consistent with our measurements. A random model that includes one or two red pigments placed close to the trap shows temperature and wavelength dependence similar to that observed experimentally. A comparison of the temperature dependence of tau 1 for cells and PSI particles is included.
莱茵衣藻仅含光系统I的突变株A4d的荧光衰减动力学被用于研究光系统I（PSI）中的能量转移和结构组织。在较宽温度范围（36 - 295 K）内，对含有约65个核心叶绿素a/P700以及来自LHC蛋白的另外60 - 70个叶绿素a + b的细胞和含有40 - 50个叶绿素a/P700的PSI颗粒进行了时间分辨测量。在每种情况下，荧光衰减动力学都由一个短成分主导，即τ1，它主要归因于核心复合物中激发态的寿命。根据模型系统中τ1的温度依赖性模拟结果对这些结果进行了讨论。模拟中明确包含了光谱不均匀性和光谱线形的温度依赖性。对包含和不包含比陷阱吸收能量低的色素（红色色素）的各种天线排列进行了建模。我们得出结论，漏斗状排列与我们的测量结果不一致。一个包含一两个靠近陷阱放置的红色色素的随机模型显示出与实验观察到的类似的温度和波长依赖性。还对细胞和PSI颗粒的τ1温度依赖性进行了比较。
