Divalent cation-induced phosphatidic acid membrane fusion. Effect of ion binding and membrane surface tension.
Divalent cation-induced phosphatidic acid membrane fusion. Effect of ion binding and membrane surface tension.
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二价阳离子诱导的磷脂酸膜融合。
DOI：
10.1016/0005-2736(85)90532-2
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发表时间：
1985
期刊：
影响因子：
--
通讯作者：
Ohshima,H
中科院分区：
文献类型：
--
作者：
Ohki,S;Ohshima,H
研究了膜融合程度与二价阳离子引起的磷脂酸膜表面张力增加之间的相关性。膜融合后进行 Tb3+/吡啶二羧酸测定，监测小单层脂质囊泡内部水成分混合的荧光强度。测量由与融合实验中使用的相同脂质制成的单层的表面张力和表面电势作为二价阳离子浓度的函数。研究发现，Ca2+ 和 Mg2+ 诱导大量囊泡膜融合的“阈值”浓度相同，并且通过将二价阳离子浓度从零改变到与其阈值相对应的浓度（诱导囊泡膜融合），单层表面张力的增加大致相同：Ca2+ 和 Mg2+ 均为 6.3 dyn/cm。磷脂酸膜的二价阳离子阈值浓度以及与阈值浓度相对应的表面张力变化均小于磷脂酰丝氨酸膜。这些二价阳离子对于磷脂酸和磷脂酰丝氨酸膜的不同融合能力根据这些离子与膜的不同离子结合能力进行讨论。
A study was made on the correlation between the degree of membrane fusion and surface tension increase of phosphatidic acid membranes caused by divalent cations. Membrane fusion was followed by the Tb3+/dipicolinic acid assay, monitoring the fluorescent intensity for mixing of the internal aqueous contents of small unilamellar lipid vesicles. The surface tension and surface potential of monolayers made of the same lipids as used in the fusion experiments were measured as a function of divalent cation concentration. It was found that the ‘threshold’ concentration to induce massive vesicle membrane fusion was the same for Ca2+and Mg2+, and that the surface tension increase in the monolayer, induced by changing divalent cation concentration from zero to a concentration which corresponds to its threshold value, inducing vesicle membrane fusion, was approximately the same: 6.3 dyn / cm for both Ca2+and Mg2+. Both the divalent cation's threshold concentrations as well as the surface tension change corresponding to the threshold concentration for the phosphatidic acid membrane were smaller than those for the phosphatidylserine membrane. The different fusion capability of these divalent cations for phosphatidic acid and phosphatidylserine membranes is discussed in terms of the different ion binding capabilities of these ions to the membranes.