Calcium/magnesium specificity in membrane fusion: kinetics of aggregation and fusion of phosphatidylserine vesicles and the role of bilayer curvature.
Calcium/magnesium specificity in membrane fusion: kinetics of aggregation and fusion of phosphatidylserine vesicles and the role of bilayer curvature.
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DOI：
10.1021/bi00514a022
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发表时间：
1981-05
期刊：
影响因子：
2.9
通讯作者：
J. Wilschut;N. Düzgüneş;D. Papahadjopoulos
中科院分区：
文献类型：
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作者：
J. Wilschut;N. Düzgüneş;D. Papahadjopoulos
Jan Wilschut、* Nejat Duzgiine §和Demetrios Papahadjopoulos* 摘要：我们研究了Ca 2+和Mg 2+诱导纯牛脑磷脂酰丝氨酸（PS）组成的磷脂囊泡融合的相对能力。通过光散射测量监测囊泡聚集，通过铽/吡啶二羧酸测定混合内部囊泡体积的融合，通过羧基荧光素荧光释放囊泡内容物，通过冷冻断裂电子显微镜观察囊泡大小的变化。使用通过超声处理制备的小单层囊泡（SUV，直径250 A）或通过反相蒸发和挤出通过聚碳酸酯膜制备的大单层囊泡（LUV，直径1000 A）。测量在25 ℃和pH7.4的0.1M NaCl介质中进行.在高于阈值浓度的Mg ~（2+）或Ca ~（2+）存在下，两种类型的囊泡都大量聚集。Mg ~（2+）不诱导LUV的融合或囊泡内容物的任何释放。它确实诱导SUV融合，这伴随着囊泡内容物的短暂释放，但融合的程度
Jan Wilschut,* Nejat Duzgiine § , and Demetrios Papahadjopoulos* abstract: We have investigated the relative abilities of Ca2+ and Mg2+ to induce the fusion of phospholipid vesicles com-posed of pure bovine brain phosphatidylserine (PS). Vesicle aggregation was monitored by light-scattering measurements, fusion by the terbium/dipicolinic acid assay for mixing of internal vesicle volumes, release of vesicle contents by car-boxyfluorescein fluorescence, andchanges in vesiclesize by freeze-fracture electron microscopy. Either small unilamellar vesicles (SUV, diameter 250 A), prepared by sonication, or large unilamellar vesicles (LUV, diameter 1000 A), prepared by reverse-phase evaporation and extrusion through a polycarbonate membrane, were used. Measurements were done in a 0.1 M NaCl medium at 25 C and pH 7.4. In the presence of either Mg2+ or Ca2+ at above-threshold concen-trations, both types of vesicles massively aggregate. Mg2+ does not induce the fusion of LUV or any release of vesicle contents. It does induce the fusion of SUV, which is accompanied by a transient release of vesicle contents, but the extent of fusion