Function of Carotenoids in Photosynthetic System and Molecular Dynamics as a Fundamenta.

研究了类胡萝卜素在光合作用中的作用，主要研究了类胡萝卜素在光合作用中作为高效天线色素的作用。重点是阐明了单线态激发态的能量传递机理。为此，开发了保留完整能量转移的完整类胡萝卜素-叶绿素蛋白复合物的分离方法。主要对色素-蛋白复合物和分离的类胡萝卜素分子进行理论和实验分析。首次从褐藻中分离到具有完全能量传递能力的叶绿素蛋白。2. 只有当类胡萝卜素的吸收最大值发生红移时才观察到能量转移，这是由于周围类胡萝卜素分子的极化性。3. 2Ag状态是通过时间分辨共振拉曼散射检测到的，这被认为是类胡萝卜素能量转移的原因。然而，由于其在复合物中的寿命很短，因此无法检测到色素-蛋白复合物中的这种状态。4. 从分离的类胡萝卜素中可以清楚地观察到荧光，并阐明了其与能量传递函数的关系。当类胡萝卜素共轭双键末端存在酮基时，类胡萝卜素激发态不对称，S1态荧光。其寿命比激发态具有对称结构的类胡萝卜素长。这两个因素可归因于高传递效率。在分离的色素-蛋白复合物中，未观察到类胡萝卜素的荧光，可能是由于其在体内的寿命短。根据叶绿素荧光的上升估计，转移时间小于2 ps。对传递过程进行了理论分析。考虑多组态波函数，计算了激励传递矩阵单元。类胡萝卜素与叶绿素S1态之间的能量转移主要取决于类胡萝卜素的对称性。在对称类胡萝卜素中，以四极-偶极相互作用为主，而在不对称类胡萝卜素中，偶极相互作用是主要的传递机制。这是第一次从理论上明确地预测了偶极相互作用是光合色素系统能量传递的可能机制。少

Function of carotenoids in photosynthesis was investigated, mainly on the function as efficient antenna pigments in light harvesting for photosynthesis. The main point is elucidation of mechanism of energy transfer through singlet excited states. For that purpose, isolation methods for intact carotenoid-chlorophyll protein complexes which retain complete energy transfer was developed. The analysis was mainly carried out theoretically and experimentally on pigment-protein complexes as well as isolated carotenoid molecules.1. Cartenold-chlorophyll protein which holds full capacity of energy transfer was isolated from the brown alga for the first time. 2. Energy transfer was observed only when the absorption maximum of carotenoid is red-shifted and this is attributed to the polarizability of surrounding molecules of carotenoids. 3. The 2Ag state was detected by the timeresolved reseonance Raman scattering, which is postulated to be responsible for the energy transfer from carotenoids. Thi … More s state in the pigment-protein complex, however, could not be detected due to its very short lifetime in the complexes. 4. Fluorescence from isolated carotenoids was clearly observed and relationship to the energy transfer function was elucidated. When a keto group is present at the end of conjugated double bond of carotenoids, which induce asymmetry in carotenoid excited state, fluorescence from the S1 state was observed. Its lifetime is longer than those of carotenoids which have symmetrical structure in their excited state. These two factors can be attributed to a high transfer efficiency. In the isolated pigment-protein complex, fluorescence from carotenoid was not observed, probably due to its short lifeitme in vivo. The transfer time, estimated from the rise of chlorophyll fluorescence was shorter than 2 ps. 5. Theoretical analysis was carried out on the transfer processes. The excitation transfer matrix element was calculated considering multiconfiguration wave functions. For the energy transfer between S1 state of carotenoid and of chlorophyll, the main mechanism changed depending on the-symmetry of carotenoids. In symmetric carotenoids, the quadrupole-dipole interaction is the predominant, on the other hand, in asymmetric carotenoids, dipoledipole interaction can be a main tranfser mechasnism. This is the first theoretical analysis which clearly predict that the dipole interaction is posssible mechanism in the energy transfer in phototosynthetic pigment systems. Less