毕氏海蓬子类囊体膜与卵磷脂重组脂质体的耐热性研究

Heat Tolerance of Salicornia bigelovii Torr. Thylakoid Complexes Reconstituted into Liposomes Constituted of L-α-Phosphatidylcholine

采用卵磷脂(PC)构建脂质体,然后将毕氏海蓬子类囊体膜蛋白复合物重组到脂质体中。分析不同温度(25℃、35℃、45℃和55℃)处理后蛋白脂质体的电子传递活性、吸收光谱和荧光光谱的变化,以探讨膜脂与膜蛋白在高温胁迫下的交互作用。结果显示:蛋白脂质体光系统Ⅱ(PSⅡ)的放氧活性和光系统Ⅰ(PSⅠ)的耗氧活性随着PC比例的提高而增加,在PC与类囊体膜比例为4∶1(Lipid∶Chl,w/w)时达到最高,同时蛋白脂质体的吸收光谱和荧光光谱也呈上升趋势;在PC与类囊体膜重组比例为4∶1条件下,高温处理后的蛋白脂质体的PSⅡ放氧活性和PSⅠ耗氧活性显著大于未经重组的,其吸收光谱和荧光光谱峰值下降幅度低于未经重组的,且峰位基本没有变化。研究表明,PC可能通过增加结合天线的大小来促进蛋白脂质体对光能的吸收和能量从外周天线到PSⅡ和PSⅠ核心复合物的传递;在脂质体中,PC与类囊体膜的交互作用提高了PSⅡ和PSⅠ在高温胁迫下的光化学效率,增强了PSⅡ和PSⅠ的耐热性。

The liposomes were constituted of L-α-Phosphatidylcholine（PC） lipids and the isolated thylakoid（Thy） complexes of Salicornia bigelovii were reconstituted into the liposomes.The electronic transport activity,absorption spectra and fluorescence spectra of proteoliposomes after different temperature treatments（25℃,35℃,45℃ and 55℃） were studied in this paper.The results showed that PSⅡ oxygen evolution activity and PSⅠ oxygen consumption activity were enhanced with increase of reconstituted PC ratio,and they reached the maximum when PC∶Thy ratio was 4∶1（Lipid∶Chl,w/w）.Moreover,the absorption spectra and fluorescence spectra were increased with increase of reconstituted PC ratio.It demonstrated that PC could enhance light absorption and energy transfer from antenna to PSⅡ and PSⅠ core complexes by increasing the antenna size and light harvest section.The PSⅡ oxygen evolution activity and PSⅠ oxygen consumption activity of reconstituted proteoliposomes at 4∶1（Lipid∶Chl,w/w） were significantly higher than that of thylakoid without reconstitution under heat stress.The decrease of absorbance spectra and fluorescence spectra of reconstituted proteoliposomes were smaller than that of thylakoid without reconstitution.And the spectra peak of reconstituted proteoliposomes did not change under heat stress.The result demonstrated the interaction between PC and thylakoid in the liposomes enhanced the photochemical activity and the heat tolerance of PSⅡ and PSⅠ under heat stress.