温度升高对PSⅡCP47/D1/D2/Cyt b559复合物能量传递的影响

采用分幅扫描单光子计数荧光光谱装置,研究温度升高对PSⅡ CP47/D₁/D₂/Cyt b559复合物能量传递的影响.获得分别在20℃、42℃和48℃处理后,CP47/D₁/D₂/Cyt b559复合物主发射峰所在的波长未发生多大改变,均在682 nm,但其荧光强度逐渐降低,而大约730 nm处主发射峰的振动副带发生了明显的变化,42℃其弱峰趋势已不显著,相对荧光强度下降,48℃弱峰趋势已完全消失;最大峰值处获得两个时间组分,这两个组分都属于电荷重组.其中,1～2 ns组分随处理温度的升高变化不大,而7～20 ns组分随温度升高变化较大,并且逐渐延长.因此,处理温度的升高使CP47/D₁/D₂/Cyt b559复合物的二级结构、色素分布的空间位置发生变化,从而影响了CP47/D₁/D₂/Cyt b559复合物中的能量传递以及电荷重组.42℃已对其造成影响,而48℃对其影响很大.

Effect of Temperature Ascending on Energy Transfer of PSⅡ Reaction Center CP47/D1/D2/CYT B559 Complex

Effect of temperature ascending on energy transfer of PSⅡ reaction center CP47/D₁/D₂/Cyt b559 complex was studied by the framing scanning single photon counting spectrum setup. CP47/D₁/D₂/Cyt b559 complex were treated at 20℃,42℃and 48℃ respectively. Their fluorescence emission spectra and lifetimes at maximum peaks were gained. The fluorescence spectra showed the relative fluorescence intensity of maximum peak at 682 nm was observed decreasing with temperature ascending, at the same time, a vibrational sub-band at about 730 nm was observed at 20℃, it decreased at 42℃ and disappeared at 48℃. The fluorescence lifetimes were: 20℃,7.14 ns and 1.97 ns;42℃,12.3 ns and 2.03 ns;48℃,19.53 ns and 1.52 ns. These lifetimes belonged to charge recombination of CP47/D₁/D₂/Cyt b559 complex. The lifetime of 7-20 ns become longer from 20℃ to 42℃. Therefore, the change of protein comformation and spatial orientation of CP47/D₁/D₂/Cyt b559 complex by ascending temperature influenced the energy transfer and charge recombination. There were more obvious changes at 42℃ and the most obvious changes at 48℃.