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

类胡萝卜素在光合系统中的功能和分子动力学基础。

基本信息

批准号：
02305014
负责人：
MIMURO Mamoru
金额：
$ 6.53万
依托单位：
Okazaki National Research Institution, National Institute for Basic Biology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Co-operative Research (A)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02305014/
关键词：
Carotenoid Photosynthesis Energy transfer Time-resolved spectroscopy Molecular dynamics Pigment-protein complex

项目摘要

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

研究了类胡萝卜素在光合作用中的作用，主要是作为有效的天线色素在光合作用中的捕光功能。重点是阐明了通过单重激发态的能量转移机制。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-蛋白质复合物和分离的类胡萝卜素分子进行了理论和实验分析。首次从褐藻胶中分离到具有完全能量传递能力的Cartenold叶绿素蛋白。2.只有当类胡萝卜素的最大吸收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率。3.时间分辨拉曼散射检测到2 Ag态，推测2 Ag态是类胡萝卜素能量转移的主要原因。Thi ...更多信息然而，由于其在复合物中的寿命非常短，因此无法检测到色素-蛋白质复合物中的S状态。4.从分离的类胡萝卜素的荧光被清楚地观察到，并阐明了能量传递函数的关系。当酮基存在于类胡萝卜素的共轭双键的末端时，其诱导类胡萝卜素激发态的不对称性，观察到来自S1态的荧光。它的寿命比在激发态具有对称结构的类胡萝卜素的寿命长。这两个因素可以归因于高转移效率。在分离的色素-蛋白质复合物中，未观察到类胡萝卜素的荧光，可能是由于其在体内的短寿命。由叶绿素荧光强度的上升估算的转移时间小于2 ps。5.对传递过程进行了理论分析。计算了考虑多组态波函数的激发转移矩阵元。对于类胡萝卜素与叶绿素之间的S1态能量传递，主要机制取决于类胡萝卜素的对称性。在对称类胡萝卜素中，四极-偶极相互作用占主导地位，而在不对称类胡萝卜素中，偶极-偶极相互作用可能是主要的传递机制。这是第一次从理论上明确地预言了偶极相互作用是光合色素系统能量传递的可能机制。少