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.

本研究旨在对研究人员在光系统I反应中心P700附近检测到的各种氧合光合成生物的叶绿素a‘(Chla’)的实际数量和体内功能部位作出结论。在建立了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下，我们分析了高等植物、嗜热蓝藻、普通蓝藻和绿藻的色素组成，得出了Chla‘/P700=1的化学计量比。结合Jordan等人于2001年报道的关于嗜热蓝藻I系统反应中心的X射线结晶学结果，最终得出结论：Chl a’是P700本身的必需成分，与正常的Chl a分子形成杂二聚体首次阐明了一种绿色硫磺细菌和一种海洋原核生物的反应中心分子组装。