Three-Pulse Photon Echo Measurements on LH1 and LH2 Complexes of Rhodobacter sphaeroides: A Nonlinear Spectroscopic Probe of Energy Transfer
Three-Pulse Photon Echo Measurements on LH1 and LH2 Complexes of Rhodobacter sphaeroides: A Nonlinear Spectroscopic Probe of Energy Transfer
复制标题
球形红杆菌 LH1 和 LH2 复合物的三脉冲光子回波测量：能量转移的非线性光谱探针
DOI：
--
复制
发表时间：
1997
期刊：
影响因子：
--
通讯作者：
G. Fleming
中科院分区：
文献类型：
--
作者：
R. Jimenez;F. V. Mourik;Jae;G. Fleming
在室温下对洗涤剂分离的LH1和LH2络合物的B875和B850谱带进行了三脉冲回波峰移测量。与通常在溶液中观察到的染料分子相比，峰位移要大得多，衰减速度也快得多。给出了基于光学跃迁频率相关函数M(T)的峰值漂移的模拟结果。M(T)包括蛋白质快速波动、振动运动和能量转移的贡献。该模型再现了B850和B875的室温吸收光谱，表明电子自由度和核自由度的耦合比染料在溶液中的耦合弱得多，并确定了对能量转移过程可能重要的线形的贡献。讨论了这些结果对LH1和LH2电子离域程度的影响。尽管相干转移的作用还有待于理解，但结果与B850和B875的弱耦合激发转移模型的使用是一致的。
Three-pulse echo peak shift measurements were performed on the B875 and B850 bands of detergent-isolated LH1 and LH2 complexes at room temperature. The peak shifts are much larger and decay much faster than typically observed for dye molecules in solution. Simulations of the peak shifts based on the optical transition frequency correlation function, M(t), are presented. M(t) includes contributions from rapid protein fluctuations, vibrational motion, and energy transfer. The model reproduces the room temperature absorption spectra of B850 and B875, shows that the coupling of electronic and nuclear degrees of freedom is much weaker than for dyes in solution, and identifies contributions to the line shapes that may be important to the energy transfer processes. The implications of these results for the extent of electronic delocalization in LH1 and LH2 are also discussed. Although the role of coherence transfer still needs to be understood, the results are shown to be consistent with the use of weak-coupling excitation transfer models of B850 and B875.