Department of Chemistry, Iowa State University, Ames, Iowa 50011-3111, USA.
J Am Chem Soc. 2011 Jan 12;133(1):141-7. doi: 10.1021/ja109036z. Epub 2010 Dec 10.
Hydrophobic interactions normally are not considered a major driving force for self-assembling in a hydrophobic environment. When macrocyclic oligocholates were placed within lipid membranes, however, the macrocycles pulled water molecules from the aqueous phase into their hydrophilic internal cavities. These water molecules had strong tendencies to aggregate in a hydrophobic environment and templated the macrocycles to self-assemble into transmembrane nanopores. This counterintuitive hydrophobic effect resulted in some highly unusual transport behavior. Cholesterol normally increases the hydrophobicity of lipid membranes and makes them less permeable to hydrophilic molecules. The permeability of glucose across the oligocholate-containing membranes, however, increased significantly upon the inclusion of cholesterol. Large hydrophilic molecules tend to have difficulty traversing a hydrophobic barrier. The cyclic cholate tetramer, however, was more effective at permeating maltotriose than glucose.
疏水相互作用通常不被认为是疏水环境中自组装的主要驱动力。然而，当大环寡胆酸盐被放置在脂质膜内时，大环将水分子从水相拉到其亲水的内部腔室中。这些水分子在疏水环境中有强烈的聚集倾向，并模板化大环自组装成跨膜纳米孔。这种有悖常理的疏水效应导致了一些非常异常的传输行为。胆固醇通常会增加脂质膜的疏水性，使它们对亲水分子的通透性降低。然而，当胆固醇被包含在内时，葡萄糖穿过含寡胆酸盐的膜的通透性显著增加。大的亲水分子往往难以穿过疏水屏障。然而，环状胆酸盐四聚体在渗透麦芽三糖方面比葡萄糖更有效。
