Pandey Santosh
Electrical and Computer Engineering, Coover Hall, Iowa State University, Ames, IA-50011, USA.
J Nanosci Nanotechnol. 2012 Mar;12(3):2489-95. doi: 10.1166/jnn.2012.5771.
Ion channels are transmembrane proteins that regulate and maintain the ionic concentrations across the cell membrane. Modeling the atomistic-level ionic flux through these channels is crucial for the understanding of several neurological diseases and related pharmaceutical discoveries. Experimental techniques now provide information about the channel's physical structure which helps in developing realisticion transport models. Ions entering a channel follow different trajectories as they traverse the channel; each associated with a certain probability. Quantities that explain these trajectories are the translocation and return probabilities, average lifetime, and spectral density (an experimentally accessible parameter) of ion number fluctuations. Theoretical analysis of ion transport has been limited to low-resolution continuum diffusion-based or kinetic-based models. Such analytical models fail to include key factors affecting the ionic conduction. In this paper, we extend previous models by an electro-diffusion model incorporating the effects of electric field, energy barrier, and rate-limited association/dissociation of ions with surface charges inside the channel. Survival probability and spectral density are derived from the analytical model.
离子通道是调节和维持细胞膜两侧离子浓度的跨膜蛋白。对通过这些通道的原子水平离子通量进行建模，对于理解多种神经疾病及相关药物研发至关重要。实验技术现在提供了有关通道物理结构的信息，这有助于开发逼真的离子传输模型。进入通道的离子在穿过通道时遵循不同的轨迹；每条轨迹都有一定的概率。解释这些轨迹的量是离子转移和返回概率、平均寿命以及离子数涨落的谱密度（一个实验上可获取的参数）。离子传输的理论分析一直局限于低分辨率的基于连续介质扩散或动力学的模型。这类分析模型未能纳入影响离子传导的关键因素。在本文中，我们通过一个电扩散模型扩展了先前的模型，该模型纳入了电场、能垒以及离子与通道内表面电荷的限速缔合/解离的影响。从该分析模型推导出了存活概率和谱密度。
