An assay to study the spontaneous charged lipid transfer between lipid vesicles is described. A donor/acceptor vesicle system is employed, where neutrally charged acceptor vesicles are fluorescently labelled with the electrostatic membrane probe Fluoresceinphosphatidylethanolamine (FPE). Upon addition of charged donor vesicles, transfer of negatively charged lipid occurs, resulting in a fluorescently detectable change in the membrane potential of the acceptor vesicles. Using this approach we have studied the transfer properties of a range of lipids, varying both the headgroup and the chain length. At the low vesicle concentrations chosen, the transfer follows a first-order process where lipid monomers are transferred presumably through the aqueous solution phase from donor to acceptor vesicle. The rate of transfer decreases with increasing chain length which is consistent with energy models previously reported for lipid monomer vesicle interactions. Our assay improves on existing methods allowing the study of a range of unmodified lipids, continuous monitoring of transfer and simplified experimental procedures.

中文翻译：

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脂质小泡之间的自发带电脂质转移。

描述了一种研究脂质小泡之间自发带电脂质转移的测定方法。使用供体/受体囊泡系统，其中用静电膜探针荧光素磷脂酰乙醇胺（FPE）对中性充电的受体囊泡进行荧光标记。在添加带电荷的供体囊泡时，发生带负电荷的脂质的转移，导致受体囊泡的膜电位在荧光上可检测到变化。使用这种方法，我们研究了各种脂质的转移特性，同时改变了头基和链长。在选择的低囊泡浓度下，转移遵循一阶过程，其中脂质单体大概通过水溶液相从供体转移到受体囊泡。转移速率随着链长的增加而降低，这与先前报道的关于脂质单体囊泡相互作用的能量模型一致。我们的检测方法对现有方法进行了改进，可以研究各种未修饰的脂质，连续监测转移过程并简化实验程序。