Mechanistic Studies of Photoactive Protein Systems

本研究将利用诱变技术和超快光谱学研究细菌光合反应中心的早期时间机制，探讨两个对称相关的电子转移途径的电子转移控制、辅助细菌叶绿素介导天线能量转移的作用以及蛋白质动力学在电子转移反应中的作用。此外，单分子荧光光谱将用于探索单反应中心/天线配合物中早期电荷转移中间体的能量学和衰减时间，以及高荧光反应中心突变体的分子间跃迁能变化。最后，利用超快光谱技术对光活性黄蛋白这一蓝光感觉复合物进行研究，以了解蛋白质运动在早期时间机制中的作用。蛋白质介导化学的机制研究仍然是现代生物化学研究的中心主题。光驱动的生物反应特别适合于这一领域的动态研究，因为整个样品的反应可以用现代脉冲激光技术以非凡的动力学分辨率启动和监测。在这个项目中，诱变和飞秒光谱学将用于研究蛋白质在控制电子转移途径中的作用，反应中心的辅助因子介导从天线捕获能量的机制，以及蛋白质动力学在太阳能转换反应中的作用。此外，还将监测单个光合配合物的发光，以研究光合反应的热力学是如何从一个复合物到另一个复合物变化的。最后，将开始研究光活性黄蛋白的飞秒动力学，这是一种参与光导细菌运动的蓝光感觉复合物。在这个系统中，蛋白质运动被认为是该机制的核心。

Woodbury9817388This research will use mutagenesis and ultrafast spectroscopy to investigate the early time mechanism of bacterial photosynthetic reaction centers by exploring the following issues: the control of electron transfer along the two symmetrically related electron transfer pathways, the role of the accessory bacteriochlorophylls in mediating energy transfer from the antenna, and the role of protein dynamics in the electron transfer reactions. In addition, single molecule fluorescence spectroscopy will be used to explore the energetics and decay times of early charge transfer intermediates in single reaction center/antenna complexes as well as the molecule-to-molecule variation in the transition energies of high-fluorescence reaction center mutants. Finally, photoactive yellow protein, a blue light sensory complex will be studied with ultrafast spectroscopy in order to understand the role of protein motion in the early time mechanism.The mechanistic study of protein-mediated chemistry remains a central theme of modern biochemical research. Light driven biological reactions have been particularly amenable to dynamic studies in this area because reactions throughout the sample can be initiated and monitored with extraordinary kinetic resolution using modern pulsed-laser techniques. In this project mutagenesis and femtosecond spectroscopy will be used to study the role of the protein in controlling the pathway of electron transfer, the mechanism by which cofactors in the reaction center mediate capture of energy from the antenna, and the role of protein dynamics in the solar energy conversion reactions. In addition, the light emission from single photosynthetic complexes will be monitored in order to study how the thermodynamics of photosynthetic reactions changed from complex to complex. Finally, a study of the femtosecond dynamics of photoactive yellow protein, a blue light sensory complex involved in light-directed bacterial movement, will be initiated. In this system, protein motion is thought to be central to the mechanism.