光系统Ⅱ核心天线的低温荧光光谱及动力学研究

采用稳态及飞秒荧光光谱技术研究了光系统Ⅱ中核心复合物在83 K、160 K和273 K低温下的能量传递途径.激发波长为507 nm.随着温度的升高,稳态荧光光谱逐渐发生蓝移.通过对不同温度下稳态光谱进行高斯解析,获得5个特征叶绿素a分子, 分别为Chl a670.4670, Chl a681.9680, Chl a683.9683, Chl a687.5,687.8,689687和Chl a698.0690,其中仅有Chl a687.5,687.8,689687在3个温度下的光谱中都解析获得,并且其谱宽以及荧光比例都随着温度升高而增加,因此推断温度对CP47中易裂解的叶绿素a分子有较大的影响.在680 nm以及690 nm波长处对不同温度下的时间曲线利用F900时间处理系统进行拟合,获得73 ps、 110 ps、 186 ps、 246~972 ps和1~3.7 ns 5个时间组分.其中, 73 ps是电荷分离的时间；110 ps和186 ps是β-Car分子受激发后,将激发能最终传递给反应中心所需要的时间；246~972 ps是电荷重组的时间过程；而1~3.7 ns是激发态分子发生电荷重组后又衰退回到基态的时间.73 ps的时间组分只在83 K温度下得到,因此,随着温度降低,可以探测到快的时间组分. 此外,对光谱随温度升高而发生蓝移进行了分析.

Low-Temperature Fluorescence Spectroscopy and Kinetics in the Photosystem II Core Complex

Low-temperature fluorescence spectroscopy and kinetics in the core complex of photosystem Ⅱ were studied with the methods of steady state and femtosecond fluorescence spectra techniques. The spectra at 83 K, 160 K and 273 K show the maximum becomes blue-shifted from 693.0 nm at 83 K to 683.0 nm at 160 K, and it is almost no shift at above 160 K.And the shoulder at long wavelength region becomes less apparent as the temperature increasing. Five groups of Chlorophyll a molecules marked as Chl a670.4670, Chl a681.9680, Chl a683.9683, Chl a687.5,687,8,689687, Chl a698.0690 were discovered from spectra at three temperatures. Based on the analyses of decay kinetics, five lifetime components were obtained to be 73 ps, 110ps, 186 ps, 246～972 ps and 1～3.7 ns. With the decreasing of temperature, the faster time component can be detected. In addition, the blue-shift of the spectrum was discussed.