Nieva J L, Goñi F M, Alonso A
Department of Biochemistry, University of the Basque Country, Bilbao, Spain.
Biochemistry. 1989 Sep 5;28(18):7364-7. doi: 10.1021/bi00444a032.
Large unilamellar vesicles composed of phosphatidylcholine/phosphatidylethanolamine/cholesterol (50:25:25 mole ratio) were treated with phospholipase C. The early stages of phospholipid cleavage are accompanied by mixing of bilayer lipids (monitored by dequenching of octadecylrhodamine fluorescence) and leakage-free mixing of vesicle contents [measured by using 8-aminonaphthalene-1,3,6-trisulfonic acid (ANTS) and p-xylylenebis(pyridinium bromide) (DPX)]. These results are interpreted in terms of vesicle fusion induced by the catalytic activity of phospholipase C. The use of sonicated unilamellar vesicles decreases the lag time, but does not modify the amplitude, of the fusion process. The presence of both phosphatidylethanolamine and cholesterol appears to be essential for measurable fusion effects to occur with low levels of phospholipid hydrolysis. Optimal fusion rates are observed with about 10-20 enzyme molecules per large unilamellar vesicle. This system of catalytically induced liposome fusion may be of relevance for the interpretation of physiological membrane fusion processes.
由磷脂酰胆碱/磷脂酰乙醇胺/胆固醇（摩尔比为50:25:25）组成的大单层囊泡用磷脂酶C处理。磷脂裂解的早期阶段伴随着双层脂质的混合（通过十八烷基罗丹明荧光猝灭监测）以及囊泡内容物的无泄漏混合[通过使用8-氨基萘-1,3,6-三磺酸（ANTS）和对二甲苯双（溴化吡啶）（DPX）测量]。这些结果根据磷脂酶C的催化活性诱导的囊泡融合来解释。使用超声处理的大单层囊泡可减少融合过程的滞后时间，但不改变其幅度。磷脂酰乙醇胺和胆固醇的存在似乎对于在低水平磷脂水解时发生可测量的融合效应至关重要。每个大单层囊泡约有10 - 20个酶分子时可观察到最佳融合速率。这种催化诱导的脂质体融合系统可能与生理膜融合过程的解释有关。
