Constrained molecular dynamics simulations have been used to investigate the LiCl and NaCl ionic association in water in terms of atom-bond electronegativity equalization method fused into molecular mechanics (ABEEM/MM). The simulations make use of the seven-site fluctuating charge and flexible ABEEM-7P water model, based on which an ion-water interaction potential has been constructed. The mean force and the potential of mean force for LiCl and NaCl in water, the charge distributions, as well as the structural and dynamical properties of contact ion pair dissociation have been investigated. The results are reasonable and informative. For LiCl ion pair in water, the solvent-separated ion pair configurations are more stable than contact ion pair configurations. The calculated PMF for NaCl in water indicates that contact ion pair and solvent-separated ion pair configurations are of comparable stability.
Molecular dynamics simulation on BPTI (biovine pancreatic trypsin inhibitor) aqueous solution has been performed for the first time in terms of the atom-bond electronegativity equalization method fused with molecular mechanics (ABEEM/MM). The simulated parameters including ABEEM parameters and force field parameters have been tested. Some structural properties including root-mean-square deviations of atomic coordinates and radial distribution functions were studied by ABEEM/MM fluctuating charge method. The results demonstrate that this model can obtain reasonable structural properties compared with experimental crystal data. The radial distribution functions indicate that ABEEM/MM method can well embody the electrostatic polarizations between protein molecule and its surrounding solvent waters.
GUAN QingMei CUI BaoQiu ZHAO DongXia GONG LiDong YANG ZhongZhi
