STRUCTURE AND FUNCTION OF CAROTENOIDS

本申请中包含的研究目的是查明 具体的结构特征，控制的速度和效率， 光合作用中发生的各种光化学过程 配合物目前的建议集中在类胡萝卜素，这是必不可少的 光合作用生物的生存。要研究的系统是 光合细菌反应中心和触角色素蛋白 复合物已经被分离、色素重构、结晶， 基因改变X射线晶体学和核磁共振光谱学将是 用作直接结构探针。光学和电子顺磁 共振光谱将允许结构与 光谱观测值和功能。反过来， 光谱观测的结构可以扩展到解释 光谱研究系统尚未结晶，从而提供了一个 理解更复杂系统的基础;例如高等植物和 藻类蛋白复合物这项建议的具体目标是：（1） 确定光合色素蛋白中类胡萝卜素的结构 （2）确定类胡萝卜素与类胡萝卜素之间的关系 结构及其光谱性质;（3）确定 类胡萝卜素结构与其作用机制之间的关系 类胡萝卜素-细菌叶绿素单线态和细菌叶绿素- 类胡萝卜素三重态能量转移几项可行性研究表明， 已经进行了支持拟议采用的方法。

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.