The effects of the macrotetralide actin antibiotics on the electrical properties of phospholipid bilayer membranes
The effects of the macrotetralide actin antibiotics on the electrical properties of phospholipid bilayer membranes
复制标题
大环四内酯肌动蛋白抗生素对磷脂双层膜电性能的影响
DOI：
10.1007/bf01869788
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发表时间：
1969
期刊：
影响因子：
--
通讯作者：
S. Ciani
中科院分区：
文献类型：
--
作者：
G. Szabó;G. Eisenman;S. Ciani
总结本文，最后在一系列的三个，表征磷脂双层膜暴露于含有nonactin，monactin，dinactin，和trinactin和Li+，Na+，K+，Rb+，Cs+，和NH 4+离子的水溶液的电性能。不仅是在零电流下的膜电阻和在零电流下的膜电位被发现依赖于抗生素和离子的水溶液浓度的方式从第一篇论文的理论预期，而且这些测量被证明是相互关联的方式所需的“中性载体”的理论。为了验证这些抗生素确实可以作为阳离子载体自由移动，将胆固醇加入脂质中以增加膜内部的“粘度”。胆固醇降低了几个数量级的macrotetralide抗生素的能力，以降低膜电阻，然而，渗透率和电导率比保持完全相同的cholesterlfree膜。最后，将观察到的nonactin、monactin、dinactin和trinactin对双层膜的影响与前一篇论文中根据盐萃取平衡常数预测的结果进行了比较;这些结果表明，第一篇文章的理论能满意地预测大环内酯类肌动蛋白抗生素对磷脂电性质的影响双层膜，仅使用第二篇论文中测得的热力学常数。因此，似乎可以合理地得出结论，这些抗生素通过溶解其中的阳离子作为移动的带正电荷的复合物而对膜产生其特征性作用。
SummaryThis paper, the last in a series of three, characterizes the electrical properties of phospholipid bilayer membranes exposed to aqueous solutions containing nonactin, monactin, dinactin, and trinactin and Li+, Na+, K+, Rb+, Cs+, and NH4+ ions. Not only are both the membrane resistance at zero current and the membrane potential at zero current found to depend on the aqueous concentrations of antibiotic and ions in the manner expected from the theory of the first paper, but also these measurements are demonstrated to be related to each other in the manner required by this theory for “neutral carriers”. To verify that these antibiotics indeed are free to move as carriers of cations, cholesterol was added to the lipid to increase the “viscosity” of the interior of the membrane. Cholesterol decreased by several orders of magnitude the ability of the macrotetralide antibiotics to lower the membrane resistance; nevertheless, the permeability ratios and conductance ratios remained exactly the same as in cholesterolfree membranes. These findings are expected for the “carrier” mechanism postulated in the first paper and serve to verify it. Lastly, the observed effects of nonactin, monactin, dinactin, and trinactin on bilayers are compared with those predicted in the preceding paper from the salt-extraction equilibrium constants measured there; and a close agreement is found. These results show that the theory of the first paper satisfactorily predicts the effects of the macrotetralide actin antibiotics on the electrical properties of phospholipid bilayer membranes, using only the thermodynamic constants measured in the second paper. It therefore seems reasonable to conclude that these antibiotics produce their characteristic effects on membranes by solubilizing cations therein as mobile positively charged complexes.