Andreoli T E, Tieffenberg M, Tosteson D C
J Gen Physiol. 1967 Dec;50(11):2527-45. doi: 10.1085/jgp.50.11.2527.
Optically black membranes prepared from sheep red cell lipids have a high electrical resistance (1-3 x 10(8) ohm-cm(2)). The ionic transference numbers (T(i)) for cations (Na(+) or K(+)) are equal to each other but at least four to five times greater than for Cl(-). The cyclic depsipeptide valinomycin produces a striking decrease in the membrane resistance when K(+), but not when Na(+) is in the solutions bathing the membrane. The ratio T(Na)/T(K), estimated from membrane voltages in the presence of ionic concentration gradients, approaches zero. The order of membrane monovalent cation selectivity, in the presence of valinomycin, is H(+) > Rb(+) > K(+) > Cs(+) > Na(+). Addition of the antibiotic to one side of a membrane which separates identical solutions of NaCl produces a substantial (up to 80 mV) membrane voltage (side opposite valinomycin negative). These data are consistent with the hypothesis that valinomycin can interact with appropriately sized cations (hydrated diameter ??? 6 A) to increase their membrane permeability, perhaps by forming hydrogen bonds between the solvation shell of the cations and carbonyl oxygens in the valinomycin molecule which are directed toward the aperture of the ring.
由绵羊红细胞脂质制备的光学黑色膜具有高电阻（1 - 3×10⁸ 欧姆·厘米²）。阳离子（Na⁺ 或 K⁺）的离子迁移数（T(i)）彼此相等，但至少比 Cl⁻ 的迁移数大四到五倍。环状缩肽缬氨霉素在膜外溶液中有 K⁺ 时会使膜电阻显著降低，而有 Na⁺ 时则不会。根据存在离子浓度梯度时的膜电压估算的 T(Na)/T(K) 比值接近零。在存在缬氨霉素的情况下，膜对单价阳离子的选择性顺序为 H⁺ > Rb⁺ > K⁺ > Cs⁺ > Na⁺。向分隔相同 NaCl 溶液的膜的一侧添加抗生素会产生显著的（高达 80 mV）膜电压（缬氨霉素所在一侧为负）。这些数据与以下假设一致：缬氨霉素可以与尺寸合适的阳离子（水合直径约为 6 Å）相互作用，可能通过在阳离子的溶剂化壳层与缬氨霉素分子中朝向环孔排列的羰基氧之间形成氢键来增加其膜通透性。
