Determination of the Functioning Site of Chlorophyll a' in the Photosynthetic Reaction Center I

光合反应中心I叶绿素a功能位点的测定

• 批准号: 12450343
• 负责人: WATANABE Tadashi
• 金额: $ 9.41万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12450343/
• 关键词: photosynthesis; chlorophyll; reaction center; HPLC; spectrophotometry; supramolecule; protein; complex; 光化学系I; クロロフィルa'; 色素; 二次電子受容体; キノン; クロロフィルa′

The present research has been conducted to draw a conclusion as to the actual number and the in vito functioning site of chloro-phyll a' (Chl a') which the researchers had detected in the vicinity of the reaction center P700 of photosystem I for a variety of oxygenic photo-synthetic organisms. After establishing HPLC conditions by which most of the chlorophylls, carotenoids/ xanthophylls and quinines can be determined in a relatively short time, we analyzed the pigment compositions of higher plants, a thermophilic cyanobacterium, regular cyanbacteria and green alga, the stoichiometry Chl a' /P700 = 1 was concluded.This, together with an X-ray crystallographic result on the system I reaction center of the thermophilic cyanobacterium, reported in 2001 by Jordan et al., finally has led to a conclusion that Chl a' is an essential component of P700 itself, forming a heterodimer with the normal Chl a molecule.In addition to these, the reaction center molecular assemblies of a green sulfur bacterium and of a marine prokaryote have been elucidated for the first time.

本研究旨在对多种含氧光合生物在光系统I反应中心P700附近检测到的叶绿素a′（Chl a′）的实际数量和体内功能位点进行总结。在建立了能在较短时间内测定大部分叶绿素、类胡萝卜素/叶黄素和奎宁的高效液相色谱条件后，我们分析了高等植物、一种嗜热蓝藻、一种普通蓝藻和绿藻的色素组成，得出了Chl a′/P700 = 1的化学计量。结合Jordan等人2001年报道的嗜热蓝藻I反应中心的x射线晶体学结果，最终得出结论：Chl a'是P700本身的重要组成部分，与正常的Chl a分子形成异二聚体。此外，还首次阐明了一种绿色硫菌和一种海洋原核生物的反应中心分子组合。