【摘要】 用蔗糖梯度离心的方法,从胰蛋白酶处理叶绿体和对照叶绿体膜分离LHC。比较研究了它们的吸收光谱、荧光光谱、圆二色光谱和荧光偏振度的变化。观测到消化叶绿体LHC的吸收光谱除位于652nm的肩消失外,其它特征性吸收均无明显改变,荧光发射峰位和在670nm的C.D.信号峰位与对照相比发生偏移,叶绿素b和吸收≤670 Nm叶绿素a的荧光偏振度降低。结果说明含叶绿素b的蛋白和短波长叶绿素a的蛋白位于类囊体膜的外侧,胰蛋白酶消化引起LHC的构型改变,从而使色素与色素、色素与蛋白的相互关系及叶绿素分子排列和方向发生改变。讨论了LHC上蛋白构型、叶绿素分子机构和叶绿素分子间能量传递的相互关系。提出了蛋白质在色素能量传递过程中的作用。更多还原

【Abstract】 Light-harvesting chlorophyll a/b-protein complex (LHC) was prepared by the sucrose density gradient centrifugation of Triton X-100-Solubilized spinach thylakoid membranes. The changes of absorption spectra, fluorescence spectra, circulardichroic spectra and fluorescence polarization of LHC from trypsin-digested and undigested membranes have been studied. The results were as follows:(1) The absorption spectrum of LHC from digested-membranes shows that the shoulder of chlorophyll b at 652 nm disappeared, but the characteristic absorption maxima at 671 nm, 466 nm and 436 nm remained the same as the undigested one.(2) The wavelengths of the fluorescence peak at 680 nm and CD signal at 670 nm of LHC shifted after trypsin treatment.(3) The fluorescence polarization of chlorophyll b and short wavelength fo m of chlorophyll a (wavelength of absorption peak≤670 nm) in LHC declined after trypsin digestion.These data suggest that chlorohyll b-containing protein and short-wave-length chlorophyll a protein are located on the outer surface of thylakoid membrane. Trypsin digestion results in preferential loss of chlorophyll b from LHC and causes the changes in protein conformation, relationship between chlorophyll-chlorophyll or chlorophyll-protein interactions and in the arrangement and the orientation of chlorophylls on LHC. This paper further discussed the relationship between protein conformation, chlorophyll molecular organization and energy transport between chlorophyll molecules, also suggested that the protein on LHC may play an important role in energy transport process between chlorophyll molecules.更多还原