Bihler H, Stark G
Department of Biology, University of Konstanz, Germany.
Biophys J. 1997 Aug;73(2):746-56. doi: 10.1016/S0006-3495(97)78107-4.
The kinetic analysis of charge pulse experiments at planar lipid membranes in the presence of macrocyclic ion carriers has been limited so far to the low voltage range, where, under certain simplifying conditions, an analytical solution is available. In the present study, initial voltages of up to 300 mV were applied to the membrane, and the voltage decay through the conductive pathways of the membrane was followed as a function of time. The system of differential equations derived from the transport model was solved numerically and was compared with the experimental data. The generalized kinetic analysis of charge pulse experiments and of steady-state current-voltage curves was used to study the voltage dependence of the individual transport steps and to obtain information on the shape of the inner membrane barrier. The data were found to be consistent with a comparatively broad inner barrier such as a trapezoidal barrier or an image force barrier. The inner barrier was found to sense 70-76% of the voltage applied to the membrane. As a consequence, 24-30% of the voltage acts on the two interfacial barriers between membrane and water. The data refer to membranes formed from monoolein, monoeicosenoin, or monoerucin in n-decane.
到目前为止，在大环离子载体存在的情况下，对平面脂质膜上电荷脉冲实验的动力学分析仅限于低电压范围，在某些简化条件下，该范围内可获得解析解。在本研究中，向膜施加高达300 mV的初始电压，并跟踪膜的导电途径上的电压衰减随时间的变化。从传输模型导出的微分方程组通过数值求解，并与实验数据进行比较。电荷脉冲实验和稳态电流-电压曲线的广义动力学分析用于研究各个传输步骤的电压依赖性，并获取有关内膜屏障形状的信息。发现数据与相对较宽的内膜屏障一致，例如梯形屏障或镜像力屏障。发现内膜屏障可感知施加到膜上70%-76%的电压。因此，24%-30%的电压作用于膜与水之间的两个界面屏障。数据涉及在正癸烷中由单油酸甘油酯、单二十碳烯酸甘油酯或单芥酸甘油酯形成的膜。
