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用同步辐射小角和宽角X光衍射实验技术研究了由二棕榈酰磷脂酰胆碱(DPPC)和豆固醇所形成的脂质体的液态有序相的结构性质.结果表明液态有序相的小角X光衍射d值(d-spacing)随着固醇温度和浓度的变化仅有微小的改变.与凝胶相及液晶相的宽角X光衍射d值相比,液态有序相的宽角X光衍射d值有更宽的变化范围, 在30-52℃的温度范围内,液态有序相的宽角X光衍射d值从0.422nm变化到0.460nm.电子云密度计算表明液态有序相的脂双层厚度和水层厚度都要大于与之平衡共存的液晶相的脂双层厚度和水层厚度.电子云密度计算结果还表明液态有序相的脂双层厚度随温度升高而降低.本研究结果对于从定量的角度认识生物膜的相态及深入认识生物膜中的有序结构具有重要意义.
The structure properties of the liquid ordered phase of liposomes formed by dipalmitoylphosphatidylcholine (DPPC) and sterol were studied by synchrotron radiation at small angle and wide angle X-ray diffraction. The results show that the liquid ordered phase The small-angle X-ray diffraction d-spacing changes only slightly with the change of the sterol temperature and concentration.Compared with the wide-angle X-ray diffraction d of gel phase and liquid crystal phase, Wide-angle X-ray diffraction d values have a wider range of variation, wide angle X-ray diffraction d value of liquid ordered phase changes from 0.422nm to 0.460nm in the temperature range of 30-52 ℃ .Electron cloud density calculation shows that liquid state Both the lipid bilayer thickness and the water layer thickness of the ordered phase are greater than the lipid bilayer thickness and the water layer thickness of the liquid crystal phase in equilibrium with it.Electron cloud density calculations also show that the lipid bilayer thickness of the liquid ordered phase varies with temperature Increase and decrease.The results of this study are of great significance for recognizing the phase state of biofilm and understanding the ordered structure in biofilm from a quantitative perspective.