Kojima H, Hanada-Yoshikawa K, Katagiri A, Tamai Y
Department of Biochemistry, Kitasato University School of Medicine, Kanagawa.
J Biochem. 1988 Jan;103(1):126-31. doi: 10.1093/oxfordjournals.jbchem.a122217.
The calorimetric properties and morphological structures of dispersed mixtures of 1, 2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and highly purified human brain gangliosides, GM2, GM1, GD1a, GD1b, and GT1b, were studied using a high-sensitivity differential scanning calorimeter and an electron-microscope, as a function of the ganglioside molar fraction. No thermal phase transitions of pure gangliosides in aqueous dispersions could be detected. In the mixtures of DPPC and gangliosides, the gel to liquid crystalline phase transition occurred at a higher temperature than in pure DPPC dispersions and progressed over a wide temperature range. As increasing amounts of the pure ganglioside species were added to DPPC, the temperature for the main transition gradually increased. The phase transition progressed differently among different gangliosides/DPPC mixtures. The enthalpy values were found to decrease linearly as the number of sialic acid residues increased. Electron-microscopically the ganglioside/DPPC mixtures formed multilamellar structures at lower concentrations of the gangliosides, and the structures changed to cylindrical and spherical micelles as the ganglioside concentration was increased. The polysialoganglioside/DPPC mixtures showed the micellar form even at lower ganglioside concentrations, contrary to the case of the monosialoganglioside/DPPC mixtures. The morphological changes of gangliosides/DPPC mixtures corresponded with changes in the calorimetric properties. These results show that individual gangliosides have different physicochemical effects on model membranes, possibly because of the interaction of their negatively charged head groups.
使用高灵敏度差示扫描量热仪和电子显微镜，研究了1,2 - 二棕榈酰 - sn - 甘油 - 3 - 磷酸胆碱（DPPC）与高度纯化的人脑神经节苷脂GM2、GM1、GD1a、GD1b和GT1b的分散混合物的热性质和形态结构，作为神经节苷脂摩尔分数的函数。在水分散体中未检测到纯神经节苷脂的热相变。在DPPC和神经节苷脂的混合物中，凝胶到液晶相的转变发生在比纯DPPC分散体更高的温度下，并且在很宽的温度范围内进行。随着越来越多的纯神经节苷脂种类添加到DPPC中，主要转变的温度逐渐升高。不同神经节苷脂/DPPC混合物之间的相变进展不同。发现随着唾液酸残基数量的增加，焓值呈线性下降。电子显微镜观察发现，在较低神经节苷脂浓度下，神经节苷脂/DPPC混合物形成多层结构，随着神经节苷脂浓度的增加，结构转变为圆柱形和球形胶束。与单唾液酸神经节苷脂/DPPC混合物的情况相反，多唾液酸神经节苷脂/DPPC混合物即使在较低的神经节苷脂浓度下也呈现胶束形式。神经节苷脂/DPPC混合物的形态变化与热性质的变化相对应。这些结果表明，单个神经节苷脂对模型膜具有不同的物理化学作用，这可能是由于其带负电荷的头部基团之间的相互作用。
