Cai M, Jordan P C
Department of Chemistry, Brandeis University, Waltham, Massachusetts 02254.
Biophys J. 1990 Apr;57(4):883-91. doi: 10.1016/S0006-3495(90)82608-4.
We describe various models for the dielectric geometry and pore mouth charge distribution of a Na channel. The electric potential due to the vestibule charges is then computed on the basis of the nonlinear Possion-Boltzmann equation. The results are used to account for the effect of permeant ion concentration and ionic strength on channel conductance and on toxin association rate constants for Na channels. We find that a single negatively charged group near the entrance to the channel constriction is adequate to account for deviations from Michaelis-Menten conductance kinetics and for the concentration dependence of toxin-binding coefficients. We find further that only a limited range of vestibule geometries and pore mouth charge distributions are consistent with experiment.
我们描述了钠通道的介电几何结构和孔口电荷分布的各种模型。然后根据非线性泊松 - 玻尔兹曼方程计算前庭电荷产生的电势。这些结果用于解释渗透离子浓度和离子强度对钠通道电导以及毒素结合速率常数的影响。我们发现通道收缩口入口附近的单个带负电基团足以解释与米氏电导动力学的偏差以及毒素结合系数的浓度依赖性。我们进一步发现只有有限范围的前庭几何结构和孔口电荷分布与实验结果一致。
