The Formation and Properties of Thin Lipid Membranes from HK and LK Sheep Red Cell Lipids
The Formation and Properties of Thin Lipid Membranes from HK and LK Sheep Red Cell Lipids
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HK和LK绵羊红细胞脂质薄脂膜的形成和性质
DOI：
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发表时间：
1967
期刊：
影响因子：
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通讯作者：
D. C. Tosteson
中科院分区：
文献类型：
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作者：
Thomas E. Andreoli;J. A. Bangham;D. C. Tosteson
用异丙醇-氯仿、氯仿-甲醇-0.1M氯化钾和氯仿依次提取高钾(HK)和低钾(LK)绵羊红细胞的脂质。提取物中胆固醇和磷脂的摩尔比为0.8：1.0，蛋白质含量小于1%。从红细胞脂-碳氢化合物溶液中形成了稳定的薄层脂膜，膜的电阻为∼108欧姆-厘米~2，电容为0.38~0.4微米/厘米~2。根据电容值，根据介电常数的假设值(2.0-4.5)，膜厚估计为46-132A。在浸泡膜的溶液中存在离子(氯化钠和/或氯化钾)浓度梯度时，记录膜电压。膜对Na+、K+和Cl-的通透性(表示为迁移数T ion)是由膜的稳态电压和隔室中离子的活度比计算出来的。TNa和TK大致相等(∼0.8)，但明显大于TCL(∼0.2)。在21-38℃范围内，离子迁移数与温度、碳氢化合物溶剂、膜的渗透压和膜的胆固醇含量无关。膜的高度阳离子选择性初步归因于脂类提取物中的带负电荷的磷脂(磷脂酰乙醇胺和磷脂酰丝氨酸)。
Lipids were obtained from high potassium (HK) and low potassium (LK) sheep red cells by sequential extraction of the erythrocytes with isopropanol-chloroform, chloroform-methanol-0.1 M KCl, and chloroform. The extract contained cholesterol and phospholipid in a molar ratio of 0.8:1.0, and less than 1% protein contaminant. Stable thin lipid membranes separating two aqueous compartments were formed from an erythrocyte lipid-hydrocarbon solution, and had an electrical resistance of ∼108 ohm-cm2 and a capacitance of 0.38–0.4 µf/cm2. From the capacitance values, membrane thickness was estimated to be 46–132 A, depending on the assumed value for the dielectric constant (2.0–4.5). Membrane voltage was recorded in the presence of ionic (NaCl and/or KCl) concentration gradients in the solutions bathing the membrane. The permeability of the membrane to Na+, K+, and Cl- (expressed as the transference number, T ion) was computed from the steady-state membrane voltage and the activity ratio of the ions in the compartments bathing the membrane. T Na and T K were approximately equal (∼0.8) and considerably greater than T Cl (∼0.2). The ionic transference numbers were independent of temperature, the hydrocarbon solvent, the osmolarity of the solutions bathing the membranes, and the cholesterol content of the membranes, over the range 21–38°C. The high degree of membrane cation selectivity was tentatively attributed to the negatively charged phospholipids (phosphatidylethanolamine and phosphatidylserine) present in the lipid extract.