PDF(Pubmed)
Abstract：
We introduce aqueous ionic liquid (IL) mixtures, specifically mixtures of 1-butyl-3-imidazoliumtetrafluoroborate (BMImBF4), with water as a minimal model of lipid bilayer membranes. Imidazolium-based ILs are known to form clustered nanoscale structures in which local inhomogeneities, micellar or lamellar structures, are formed to shield hydrophobic parts of the cation from the polar cosolvent (water). To investigate these nanostructures, dynamic light scattering (DLS) on samples with different mixing ratios of water and BMImBF4 was performed. At mixing ratios of 50% and 45% (v/v), small and homogeneous nanostructures can indeed be detected. To test whether, in particular, these stable nanostructures in aqueous mixtures may mimic the effects of phospholipid bilayer membranes, we further investigated their interaction with myelin basic protein (MBP), a peripheral, intrinsically disordered membrane protein of the myelin sheath. Using dynamic light scattering (DLS), continuous wave (CW) and pulse electron paramagnetic resonance (EPR), and small-angle X-ray scattering (SAXS) on recombinantly produced, \"healthy\" charge variants rmC1WT and double cysteine variant C1S17CH85C, we find that the size and the shape of the determined nanostructures in an optimum mixture offer model membranes in which the protein exhibits native behavior. SAXS measurements illuminate the size and shape of the nanostructures and indicate IL-rich \"beads\" clipped together by functional MBP, one of the in vivo roles of the protein in the myelin sheath. All the gathered data combined indicate that the 50% and 45% aqueous IL mixtures can be described as offering minimal models of a lipid mono- or bilayer that allow native processing and potential study of at least peripheral membrane proteins like MBP.
摘要：
我们引入水性离子液体（IL）混合物，特别是四氟硼酸1-丁基-3-咪唑三醇（BMImBF4）的混合物，以水作为脂质双层膜的最小模型。已知基于咪唑的IL形成簇状的纳米级结构，其中局部不均匀性，胶束或层状结构，形成以屏蔽阳离子的疏水性部分与极性共溶剂(水)。为了研究这些纳米结构，在具有不同水和BMIMBF4混合比的样品上进行动态光散射(DLS)。在50%和45%(v/v)的混合比下，确实可以检测到小且均匀的纳米结构。要测试是否，特别是,这些稳定的纳米结构在水性混合物中可以模拟磷脂双层膜的作用，我们进一步研究了它们与髓磷脂碱性蛋白（MBP）的相互作用，外围，髓鞘的内在无序的膜蛋白。使用动态光散射（DLS），连续波（CW）和脉冲电子顺磁共振（EPR），和重组产生的小角度X射线散射（SAXS），“健康”电荷变体rmC1WT和双半胱氨酸变体C1S17CH85C，我们发现，最佳混合物中确定的纳米结构的大小和形状提供了模型膜，其中蛋白质表现出天然行为。SAXS测量阐明了纳米结构的大小和形状，并表明富含IL的“珠子”被功能性MBP夹在一起，蛋白质在髓鞘中的体内作用之一。所有收集的数据组合表明,50%和45%水性IL混合物可以被描述为提供脂质单层或双层的最小模型,其允许天然加工和至少外周膜蛋白如MBP的潜在研究。
