Effect of the membrane surface charge on the host-guest complex of valinomycin in a synthetic lipid monolayer at the air-water interface
Effect of the membrane surface charge on the host-guest complex of valinomycin in a synthetic lipid monolayer at the air-water interface
复制标题
膜表面电荷对空气-水界面合成脂质单层中缬氨霉素主客体复合物的影响
作者：
M. Sugawara;H. Sazawa;Y. Umezawa
通过测定膜表面压力-分子面积等温线，研究了膜表面电荷对合成脂单分子膜中呋喃霉素分子与K~(2+)离子的络合作用的影响。研究发现，当呋喃霉素包埋在带有负电荷的头基团如十二烷基磷酸酯的脂单分子膜中时，K[sup+]/valinmycin络合物的形成。相反，包埋在阳离子脂单分子膜(如双十八烷基二甲基溴化铵)中或与不含脂类的纯呋喃霉素单分子膜形成络合物的证据不明显。结果表明，带负电荷的脂类的使用是在混合单层组装中形成K[sup+]/valinmycin络合阳离子的先决条件，从而为膜环境中的电中性提供了阴离子中心。此外，在混合单层组装中发现两个组分，呋喃霉素和磷酸十二烷基酯是不相容的，这表明K[sup+]/呋喃霉素复合体可能形成的位置是在两个不相容的微单层结构域的边界上。参考文献19，图4，表1。
The effect of the membrane surface charge on the host-quest complexation of valinomycin molecules with K[sup +] ions in synthetic lipid monolayers was studied by measuring surface pressure-molecular area isotherms. It was found that the formation of K[sup +]/valinomycin complexes took place when valinomycin was embedded in the monolayer of lipid with negatively charged head groups, such as didodecyl phosphate. On the contrary, no evidence for the complex formation was observed with valinomycin embedded into cationic lipid monolayers such as dioctadecyldimethylammonium bromide monolayer, or with a pure valinomycin monolayer without lipid. It was concluded that the use of negatively charged lipids was a prerequisite for the formation of the K[sup +]/valinomycin complex cation in the mixed monolayer assembly, thereby providing anionic sites for electroneutrality in the membrane environment. Furthermore, the result that two components, valinomycin and didodecyl phosphate, were found immiscible in the mixed monolayer assembly indicated that a possible location for the K[sup +]/valinomycin complex to be formed was at the boundary of the two immiscible micro-monolayer domains. 19 refs., 4 figs., 1 tab.