STRUCTURE AND FUNCTION OF CAROTENOIDS

本申请中包含的研究的目标是准确地确定 控制速度和效率的特定结构特征 光合作用中发生的各种光化学过程 复合体。目前的建议集中在类胡萝卜素上，这是必不可少的 为了光合作用有机体的生存。拟研究的系统包括 光合作用细菌反应中心与天线色素蛋白 已分离、色素重组、结晶和 经过基因改造。X射线结晶学和核磁共振光谱将是 用作直接结构探针。光学和电子顺磁 共振光谱学将允许将结构与 光谱可观测性和功能。反过来，它们之间的关系 对结构的光谱观测可以扩展到解释 对尚未结晶的体系的光谱研究，从而提供了 了解更复杂系统的基础；例如，高等植物和 藻类蛋白质复合体。这项建议的具体目的是：(1) 测定光合色素蛋白中类胡萝卜素的结构 确定类胡萝卜素之间的关系； 结构及其光谱性质；以及(3)确定 类胡萝卜素结构与其作用机制的关系 类胡萝卜素到细菌叶绿素单线态和细菌叶绿素到-- 类胡萝卜素三联体能量转移。几项可行性研究已经 已经为支持拟采用的方法而开展了工作。

The objective of the research contained in this application is to pinpoint specific structural features which control the rates and efficiencies of the various photochemical processes which take place in photosynthetic complexes. The present proposal focuses on carotenoids which are essential for the survival of photosynthetic organisms. The systems to be studied are photosynthetic bacterial reaction center and antenna pigment-protein complexes which have been isolated, pigment-reconstituted, crystallized and genetically altered. X-ray crystallography and NMR spectroscopy will be used as direct structural probes. Optical and electron paramagnetic resonance spectroscopy will allow the correlation of structure with spectroscopic observables and function. In turn the relationships of the spectroscopic observables to the structures may be extended to interpret spectroscopic studies on systems not yet crystallized, thus providing a basis from which to understand more complex systems; e.g. higher plant and algal protein complexes. The specific aims of this proposal are: (1) To determine the structures of carotenoids in photosynthetic pigment-protein complexes; (2) To determine the relationships between the carotenoid structures and their spectroscopic properties; and (3) To determine the relationships between the carotenoid structures and their mechanisms of carotenoid-to-bacteriochlorophyll singlet and bacteriochlorophyll-to-- carotenoid triplet energy transfer. Several feasibility studies have already been carried out in support of the methods proposed to be employed.