ELECTRIC FIELD EFFECTS ON PHOTOSYSTEM II ELECTRON TRANSFER

电场对光系统 II 电子传输的影响

• 批准号: 6120124
• 负责人: PETER LESLIE DUTTON
• 金额: $ 0.27万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-08-01 至 2000-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6120124
• 关键词: biological products; biomedical resource; lasers; proteins

We have developed ways of measuring electron transfer dynamics in specially designed capacitors made from membrane bound reaction center protein. This has demanded the design of critical coupling protocols between femtosecond pulses and the creation of fields across the structure. From the spectroscopic standpoint the great challenge is to improve the signal-to noise in fs experiments where the sample cannot be moved or flowed. Furthermore, the coupling of such experiments to pulsed electric fields and concerning demonstrations of the presence of transient fields is nontrivial. The free energy of the initial charge separation in bacterial photosynthetic reaction centers has been modified by placing oriented Langmuir-Blodgett films of the purified protein between external electrodes in a planar capacitor and applying a field of nearly 106 V/cm. The near-infrared transient absorption changes associated with the decay of the excited state of the bacteriochlorophyll d imer and t he initial charge separation was measured with 300 fs time resolution with and without applied field. The surprisingly small field induced rate changes of the oriented systems compared to unoriented systems suggest that modulation of the energy gap between excited bacteriochlorophyll dimer and the charge separated state with bacteriochlorophyll monomer reduced is the principal influence of electric field on rate. The field induced quantum yield failure observed at longer timescales appears to be associated with modulation of the bacteriopheophytin to bacteriochlorophyll dimer charge recombination.

我们已经开发了测量电子传输动力学的方法 由膜结合反应中心制成的专门设计的电容器 蛋白质。 这要求设计关键耦合方案 飞秒脉冲与跨越田野的创建之间 结构。 从光谱的角度来看，巨大的挑战是 在FS实验中提高信号噪声，其中样品 无法移动或流动。 此外，这种耦合 脉冲电场的实验以及有关的证明 瞬态场的存在是非平凡的。 自由能 细菌光合反应中的初始电荷分离 通过放置定向的langmuir-blodgett膜来修改中心 平面中外电极之间的纯化蛋白 电容器并应用近106 v/cm的场。 近红外 与激发的衰变相关的瞬态吸收变化 细菌谷物植物的状态和初始电荷 用和不带有300 FS的时间分辨率测量分离 应用字段。 令人惊讶的小场引起的速率变化 与非导向系统相比，面向的系统表明 调节激发型谷物叶子二聚体之间的能量差距 电荷与细菌谷物叶子单体分离状态 减少是电场对速率的主要影响。 这 场诱导的量子产量失败在更长的时间尺度上观察到 似乎与噬菌素的调节至 细菌绿化二聚体电荷重组。