A nuclear magnetic resonance study of alamethicin-, δ-haemolysin-, and melittin-induced sodium leakage from large unilamellar vesicles
A nuclear magnetic resonance study of alamethicin-, δ-haemolysin-, and melittin-induced sodium leakage from large unilamellar vesicles
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阿拉甲辛、δ-溶血素和蜂毒肽诱导的大单层囊泡钠泄漏的核磁共振研究
DOI：
10.1042/bst0160594
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
I. Campbell
中科院分区：
文献类型：
--
作者：
G. King;J. Deegan;Ross Smith;A. Matouschek;I. Campbell
大多数跨膜离子通量的核磁共振（nmr）研究都采用细胞外移位试剂来分离离子的细胞内和细胞外nmr信号（例如，Viero & Hunt，1986）。这使得能够获得关于离子通量的动力学的信息，但不能获得关于其机制和异质性的信息。为了克服这一局限性，我们研究了肽诱导的钠泄漏从大的单层囊泡（LUVs）装载intravesicularly与转换试剂。这提供了每个囊泡内离子浓度的指示，因为细胞内离子信号的化学位移取决于[位移试剂]/[离子]比。使用蛋黄磷脂酰胆碱通过反相蒸发制备LUV（170 nm直径）（Szoka和Papahadjopoulos，1978）。它们负载有150 mM NaCl和1.75 mM-三聚磷酸镝[Dy（PPPJ-1）;该复合物诱导囊内钠（Na+）共振的高场超精细位移。囊外介质为等渗蔗糖。从这些LUV被动Na+泄漏的渗透系数使用“nmr = 2 x 10-”cm/s确定;文献
Most nuclear magnetic resonance (nmr) studies of transmembrane ion fluxes have employed extracellular shift reagents to separate intra-and extra-cellular nmr signals of the ion (eg. Viero & Hunt, 1986). This enables information to be gained about the kinetics of ion flux, but not about its mechanism and heterogeneity. To obviate this limitation, we studied peptide-induced sodium leakage from large unilamellar vesicles (LUVs) loaded intravesicularly with shift reagent. This provides an indication of the ion concentration within each vesicle because the chemical shift of the intracellular ion signal is dependent on the [shift reagent]/[ion] ratio. Thus, information about mechanism and heterogeneity can be obtained.LUVs (170 nm diameter) were prepared by reverse phase evaporation using egg yolk phosphatidylcholine (Szoka & Papahadjopoulos, 1978). They were loaded with 150 mMNaCl and 1.75 mM-dysprosium tripolyphosphate [Dy (PPPJ-1; this complex induces an upfield hyperfine shift of the intravesicular sodium (Na;,) resonance. The extravesicular medium was iso-osmolar sucrose. The permeability coefficient for passive Na+ leakage from these LUVs was determined using'" a nmr to be 2 x lo-" cm/s; literature