Abstract:

Fluorescence properties of light-harvesting complex LHCⅡ） in photosystem Ⅱ isolated from spinach (Spinacia oleracea L.) was investigated with the time-resolved fluorescence spectroscopic technique. The sample was excited by double frequency Ti:Al203 laser with 400 nm wavelength and 120 fs width. Fluorescence signal was detected by Boxcar. Three life-time components （320 fs，4.0 ps and 20.0 ps） were obtained by multi-exponential curve model and nonlinear least-square fitting method. Three fluorescence peaks （652 nm, 672 nm, 691 nm） were obtained by Global analysis and Gauss curve fitting. These components were analyzed according to the structural and fluorescence spectroscopic property of LHCⅡ. The fluorescence ratio of each component to that of all the component was 3.4%, 50% and 46.6% respectively. The possible model of energy transfer in LHCⅡ was discussed.

光系统II捕光复合体飞秒时间分辨荧光特性的研究
任兆玉^1,2,3 贺俊芳^1,2 王水才¹侯洵^1,2  匡廷云⁴

（1. 中国科学院西安光学精密机械研究所瞬态光学技术国家重点实验室，西安710068；
2.  西北大学光子学与光子技术研究所，西安710068；3. 西北工业大学应用物理系，西安710072；
4. 中国科学院植物研究所光合作用基础研究开放实验室，北京100093）

摘要：采用时间分辨荧光光谱技术研究了菠菜(Spinacia oleracea L.)叶绿体中捕光色素复合体 (LHCⅡ) 荧光的时间特性和光谱特性.用脉宽为120 fs、波长为400 nm的倍频钛宝石激光激发LHCⅡ样品;原始荧光信号由Boxcar采集,通过建立多指数模型,用非线性最小二乘法拟合,得到了激发能在LHCⅡ中传递的时间常数分别为:320 fs、4.0 ps和20.0 ps.相对应的各组分荧光占总荧光的百分比分别为:3.4％、50.0％和46.6％.经全局分析,解得荧光强度随波长变化曲线;用高斯3峰解叠得到荧光光谱的峰值波长分别为:652 nm、672 nm和691 nm.通过分析得出了时间常数与LHCⅡ中各色素成分之间的对应关系,并给出了可能的能量传递模型.

关键词： 捕光复合体（LHCII）；能量传递；时间常数；荧光特性；Chl a/b

Key words: light-harvesting complex, energy transfer, time constant, fluorescence properties, Chl a/b