The Role of Xanthophylls in the Mechanism of Nonradiative Energy Dissipation in Photosynthesis

光合作用有机体包含保护机制，通过这种机制，多余的光能在导致光合作用装置的光破坏之前被消散。此外，从捕光色素-蛋白质复合体到光合作用反应中心的能量流动也受到高度调控。这些过程的控制特征还没有被很好地理解。叶黄素色素被认为与这些机制有关，但它们参与的确切性质尚不清楚。为了解决这一问题，将进行稳态吸收、荧光、双光子激发以及时间分辨吸收和荧光光谱实验。这些实验将探索叶黄素激发态的能量和电子构型，并测量叶黄素和叶绿素之间的能量转移效率和动力学。此外，还将进行电化学分析，以检查分子的氧化电位。所研究的叶黄素在结构、π电子共轭程度、激发态能量和氧化电位等方面存在差异。这项研究将通过对从高等植物和藻类中分离出来的天然、重组和重组的色素蛋白复合体中的这些分子的系统研究，准确地研究能量耗散和能量流调节是如何完成的。这项研究的主要目的是检查每个被认为在这些过程中重要的分子因素，以揭示它们在体内发生的详细机制。这项工作有望更好地了解植物如何将太阳能转化为化学能，并在过剩的太阳能条件下承受压力。这项研究的更广泛影响包括让参与研究的学生获得生物材料分离、提纯和表征技术以及复杂的光学光谱方法的经验。他们的部分培训将包括撰写论文和在科学会议上发言，在这些会议上将公开传播研究结果。这个项目还包括一名本科生院校的教职员工参与。他直接参与该项目将扩大他的研究视野，并将对一所文科本科院校的科学教育产生影响。

Photosynthetic organisms contain protective mechanisms by which excess light energy is dissipated before it leads to the photodestruction of the photosynthetic apparatus. Also, energy flow from light-harvesting pigment-protein complexes to the photosynthetic reaction center is highly regulated. The controlling features of these processes are not well understood. Xanthophyll pigments have been implicated in the mechanisms, but the precise nature of their involvement is unclear. In order to address this issue steady state absorption, fluorescence, two-photon excitation, and time-resolved absorption and fluorescence spectroscopic experiments will be performed. These experiments will probe the energies and electronic configurations of the excited states of the xanthophylls and measure the efficiencies and dynamics of energy transfer between the xanthophylls and chlorophylls. Also, electrochemical analyses will be done to examine the oxidation potentials of the molecules. The xanthophylls to be studied differ in their structures, extents of pi-electron conjugation, excited state energies and oxidation potentials. This research will investigate precisely how energy dissipation and energy flow regulation are accomplished through a systematic study of these molecules in native, recombinant, and reconstituted pigment-protein complexes isolated from higher plants and algae. The major objective of this study is to examine each of the molecular factors thought to be important in these processes in order to reveal the detailed mechanisms by which they take place in vivo. This work is expected to lead to a better understanding of how plants convert solar energy into chemical energy and withstand stress under excess solar energy conditions.The broader impacts of this study include having the participating students obtain experience in the techniques for the isolation, purification and characterization of biological materials and in sophisticated optical spectroscopic methodologies. Part of their training will include writing papers and making presentations at scientific meetings at which the results of the studies will be openly disseminated. This project also involves the participation of a faculty member from an undergraduate institution. His direct involvement in the project would expand his research horizons and will have an impact on the science education at a liberal arts undergraduate institution.