糖和盐类物质对生物膜超分子结构稳定性影响的研究

Effect of Saccharide and Salts on the Stability of Super-Molecular Ordered Structure of Simulated Biomembrane

用原子力显微镜(AFM)和小角X射线(SAXS)技术,研究了NaCl、KCl、胆固醇、葡萄糖和蔗糖等与膜脂的相互作用.研究发现它们能引起脂质膜超分子体系液晶态结构的变化.葡萄糖和蔗糖对脂双层膜结构有稳定作用.在NaCl溶液中制成的脂质膜,随着NaCl浓度的增加,它们的双层膜更稳定.在KCl溶液中结果恰好相反.AFM研究发现液晶态脂双层膜结构与双亲性分子的结构、浓度以及介质的组分和pH等因素有关.在1,2-反十八碳-3-磷脂酰乙醇胺(DEPE)液晶态中,钠盐诱导形成Q229(Im3m)立方相.油酸的含量对DEPE-PVP(聚乙烯吡咯烷酮)超分子结构也有一定的影响,当油酸含量达到某一临界值时,则发生从Im3m(Q229)到Pn3m(Q224)的转变.胆固醇能促使形成Pn3m(Q224)和六角相HII共存相.研究结果表明,生物膜超分子聚集体的氢键、分子vanderWaals力、离子的静电力等这些弱相互作用的协同性、方向性和选择性,可能决定着生物膜的结构和功能.

A study by the technique of modem physics has been made on the interaction between NaC1, KC1, polyvinyl-pyrolidone （PVP）, cholesterol （Chol）, glucose and sucrose solutions separately and lipids. It was found that they can make conformational change of super-molecular system in the liquid crystalline state. There are stable effects of the glucose and sucrose solutions on the structure of lipid bilayer membranes. When the lipid bilayer membranes are prepared in NaCl-solutions, they are more stable with increasing NaC1 concentration. For KC1 it is just the opposite. By the atomic force microscope, a structure of cubic phase and bilayer phase of phosphoethanolamine （PE） was observed. The structure is closely related to the structure of amphoteric molecules, concentration, medium and pH. It was found that sodium salt solutes induce formation of an Im3m（Q^229） cubic phase in DEPE dispersions. A structure transition from Im3m（Q^229） to Pn3m（Q^224） occurred with increasing PVP concentration in the DEPE-PVP super-molecular structures. The effect of oleic acid （OA） on DEPE（1,2-dielaidoyl-sn-glycero-3-phosphoethanolamine）-PVP supermolecular structures was determined using a certain fixed amount. At a critical concentration of OA, a structure transition from Im3m（Q^229） to Pn3m（Q^224） occurred. The cholesterol promotes formation of a coexisting Pn3m（Q^224） and hexagonal HⅡ structure. The experiments proved that the structure and function of biologic super-molecular system maybe rest with the cooperativity, directivity and selectivity of hydro-gen-bonded interaction, van der Waals interaction, and electric interaction.