Abstract:

Surfactants are widely used in the purification and research of structure and function of the protein complexes in photosynthetic membrane. To elucidate the mechanism of interaction between surfactants and photosystem Ⅰ (PSⅠ), effects of two typical surfactants, Triton X-100 and sodium dodecyl sulfate (SDS) on PSⅠ, were studied at different concentrations. The results were: SDS led to the reduction of apparent absorption intensity and blue shift of absorption peaks; while Triton X-100 led to the decrease of apparent absorption intensity in red region and blue shift of the peak, but to the increase of apparent absorption intensity in blue region. The fourth derivative spectra show that the longwavelength (669 nm and 683 nm) absorbing chlorophyll a was affected greatly and their relative changes of absorbance were axially symmetrical. The presence of surfactant could make the long wavelength fluorescence emission decrease greatly and a new fluorescence peak appeared around 680 nm, it was obvious that the surfactant interceded the transfer of excitation energy from antenna pigments to reaction center. The surfactants might affect the microenvironment of proteins, even the structure of PSⅠ protein subunits and hence changed the binding status of pigments with protein subunits, or the pigments might be released from the subunits. All of these might affect the absorption and the transfer of excitation energy.

表面活性剂对小麦光系统I叶绿素结合状态和能量传递的影响
郁飞¹ 唐崇钦^1* 辛越勇¹ 彭德川¹ 李良璧¹

匡廷云¹ 李济云² 李振声2

（1.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；
2.中国科学院遗传研究所，北京100101）

摘要：表面活性剂在光合膜色素蛋白复合物的分离纯化和结构功能研究中有十分广泛的应用。为了探讨表面活性剂与光系统Ⅰ(psⅠ)的相互作用机理,选择了两种具代表性的表面活性剂trit on x-100和十二烷基磺酸钠(sds),选取一系列浓度值研究了它们对psⅠ的影响。结果表明,sds处理时,psⅠ在红区和蓝区的表观吸收峰值下降,峰位蓝移;triton x-100使红区吸收峰值下降,峰位蓝移,但却使psⅠ颗粒蓝区表观吸收升高。四阶导数光谱显示小麦(triticum aestivum l.) psⅠ颗粒中较长吸收波长的669 nm和683 nm状态叶绿素a分子受影响较大,两者吸光度值互为消长且变化呈轴对称形式,而649 nm组分(叶绿素b)在两者作用下变化较小。表面活性剂使psⅠ颗粒长波长荧光急剧下降,并在680 nm左右出现新的荧光发射峰,可见其阻碍了激发能由天线色素向反应中心的传递。以上的变化说明sds和triton x-100对psⅠ载体蛋白的微环境甚至结构产生影响而导致色素与蛋白结合状态发生改变,或从蛋白上脱落下来 ,最终影响到光能的吸收和能量传递。

关键词： 表面活性剂；光系统!；叶绿素；吸收光谱；荧光光谱

Key words: surfactant, Photosystem Ⅰ, chlorophyll, absorption spectra, fluorescence spectra