Zhang Hai-lin

Properties of Hydrated Alkali Metals Aimed at the Ion Channel Selectivity

The hydration structure properties of different alkali metal ions with eight water molecules and potassium ions with different numbers of water molecules are studied using the mixed density functional theory, B3LYP, with 6-311G basis set. The hydration structures are obtained from structure optimization and the optimum numbers of water molecules in the innermost hydration shell for the alkali metal ions are found. Some useful information about the ion channel selectivity is presented.

Identification of Three Interactions to Determine the Conformation Change and to Maintain the Function of Kir2.1 Channel Protein

We find that a conserved mutation residue Glu to residue Asp (E303D), which both have the same polar and charged properties, makes Kir2.1 protein lose its function. To understand the mechanism, we identify three interactions which control the conformation change and maintain the function of the Kir2.1 protein by combining homology modeling and molecular dynamics with targeted molecular dynamics. We find that the E303D mutation weakens these interactions and results in the loss of the related function. Our data indicate that not only the amino residues but also the interactions determine the function of proteins.

Cooperative Car-Following Model of Traffic Flow and Numerical Simulation

Based on the impact of a desired following speed and safe distance on driving behaviour, we establish a cooperative car-following model (CCFM). The dynamics analysis results indicate that no unrealistic deceleration or collision occurs in the CCFM. Also, this model can describe the kinetic property in the processes of starting and braking. In addition, evolution of a small perturbation can be reproduced in a numerical simulation. Compared to the full velocity difference model (FVDM), the CCFM has a wider range of stability and a much smaller blocking region width. Meanwhile, the CCFM averts negative velocity, and is accordingly advanced compared with the comprehensive optimal velocity model (COVM). Moreover, the CCFM describes the deceleration process more smoothly than both the FVDM and COVM.

Electrostatic Interactions Determining the Selectivity of KcsA Channel and Its Mutants

We perform the density functional theory and Brownian dynamics simulations based on the three-dimensional structure of the WT KcsA channel and its mutants. Our data suggest that the electrostatic interactions between the channels and cations, within the signature sequence of K+ channels, determine the selectivity of the channel.