鞘磷脂和神经节苷脂对磷脂酰乙醇胺混合脂超分子体系液晶态立方相Im3m和Pn3m结构影响的研究

用磷脂酰乙醇胺(DEPE)、鞘磷脂(Sphingomyeline, Sph)、神经节苷脂(Gm1)和胆固醇(Chol)模拟了生物膜超分子体系液晶态结构, 通过用小角X射线衍射(SAXD)对混合脂体系液晶态结构进行了研究, 鉴定出了两种立方相: 即Im3m(Q²²⁹)和Pn3m(Q²²⁴)结构. 实验发现, 鞘磷脂的含量对DEPE膜的结构有一定的影响, 随着鞘磷脂浓度的增加, 混合脂体系的液晶态结构发生了由Im3m(Q²²⁹)到Pn3m(Q²²⁴)的变化. 神经节苷脂(Gm1)的含量对混合脂体系的液晶态结构也有一定的影响, 当神经节苷脂(Gm1)含量达到某一临界值时, 混合脂体系的液晶态结构发生了从Im3m(Q²²⁹)到Pn3m(Q²²⁴) 的变化. 当DEPE-Shp-Gm1超分子聚集体中含有胆固醇时, 胆固醇的极性头部(—OH)与磷脂酰乙醇胺(DEPE)、鞘磷脂(Shp)、神经节苷脂(Gm1)的极性头部通过氢键相互作用形成液晶态立方相Im3m(Q²²⁹)结构, 再通过疏水/亲水相互作用形成稳定的Pn3m (Q²²⁴)结构.

Effect of Sphingomyeline and Monosialioganglioside-Gm1 on the Phase Behavior of the Super-molecular Structures of 1,2-Dielaidoyl-sn-glycero-3-phosphatidyl-ethanolamine: Cubic Phase Im3m to Pn3m Transition in Liquid Cryst

It has been investigated that the super-molecular structures in liquid crystalline states are made up of DEPE (1,2-dielaidoyl-sn-glycero-3-phosphatidyl-ethanolamine), sphingomyeline, monosialioganglioside-Gm1 and cholesterol by small angle X-ray diffraction. The effect of sphingomyeline on DEPE film was determined. A structure transition from Im3m(Q²²⁹) to Pn3m(Q²²⁴) occurred with increasing sphingomyeline concentration in the super-molecular structures. The effect of monosialioganglioside-Gm1 content on the super-molecular structures was also determined. At a critical concentration of monosialioganglioside-Gm1, the structure transition from Im3m(Q²²⁹) to Pn3m(Q²²⁴) occurred. The effect of the addition of cholesterol on DEPE-Shp-Gm1 super-molecular structure has also been investigated. There exists an interaction between the polar head (—OH) of cholesterol and that of DEPE, sphingomyeline, monosialioganglioside-Gm1 by oxygen-halogen bond, to form cubic phase of liquid crystalline states. A Pn3m(Q²²⁴) structure was further formed by hydrophilic/hydrophobic interaction.