论文标题
低渗溶液中二元电荷脂质膜的三相共存
Three-phase coexistence in binary charged lipid membranes in hypotonic solution
论文作者
论文摘要
我们研究了使用荧光和共聚焦激光扫描显微镜在低音溶液中巨型Unilamelar囊泡中二烯酰磷脂酰丝氨酸（DOPS）和二甲米酰磷脂酰胆碱（DPPC）的相分离。尽管电荷脂质膜中的相位分离通常被带电头组之间的静电排斥抑制，但渗透应激可以促进带电脂质结构域的形成。有趣的是，即使在DOPS/DPPC二元脂质混合物中，我们也观察到三相共存。这三个阶段富含DPPC，富含DOPS和非分离型垃圾杆相。由于DOPS头组的电离，因此发现两种形式的DOP是共存的，因此可以将系统视为准内部。通过监测正电荷颗粒的吸附，成功地鉴定出具有不同电离的DOPS结构域的三个形成的相位。此外，粗粒分子动力学模拟证实了三相共存的稳定性。由质子化的DOP分子之间的氢键介导的吸引力和在域边界处的静电相互作用的还原稳定了三相共存。
We investigated the phase separation of dioleoylphosphatidylserine (DOPS) and dipalmitoylphosphatidylcholine (DPPC) in giant unilamellar vesicles in hypotonic solution using fluorescence and confocal laser scanning microscopy. Although phase separation in charged lipid membranes is generally suppressed by the electrostatic repulsion between the charged headgroups, osmotic stress can promote the formation of charged lipid domains. Interestingly, we observed three-phase coexistence even in DOPS/DPPC binary lipid mixtures. The three phases were DPPC-rich, dissociated DOPS-rich, and nondissociated DOPS-rich phases. The two forms of DOPS were found to coexist owing to the ionization of the DOPS headgroup, such that the system could be regarded as quasi-ternary. The three formed phases with differently ionized DOPS domains were successfully identified experimentally by monitoring the adsorption of positively charged particles. In addition, coarse-grained molecular dynamics simulations confirmed the stability of the three-phase coexistence. Attraction mediated by hydrogen bonding between protonated DOPS molecules and reduction of the electrostatic interactions at the domain boundaries stabilized the three-phase coexistence.
