No K T, Kim S G, Cho K H, Scheraga H A
Department of Chemistry and CAMD Research Center, Soong Sil University, Seoul 156-743, Korea.
Biophys Chem. 1999 Apr 5;78(1-2):127-45. doi: 10.1016/s0301-4622(98)00225-7.
A method to calculate the solvation free energy density (SFED) at any point in the cavity surface or solvent volume surrounding a solute is proposed. In the special case in which the solvent is water, the SFED is referred to as the hydration free energy density (HFED). The HFED is described as a function of some physical properties of the molecules. These properties are represented by simple basis functions. The hydration free energy of a solute was obtained by integrating the HFED over the solvent volume surrounding the solute, using a grid model. Of 34 basis functions that were introduced to describe the HFED, only six contribute significantly to the HFED. These functions are representations of the surface area and volume of the solute, of the polarization and dispersion of the solute, and of two types of electrostatic interactions between the solute and its environment. The HFED is described as a linear combination of these basis functions, evaluated by summing the interaction energy between each atom of the solute with a grid point in the solvent, where each grid point is a representation of a finite volume of the solvent. The linear combination coefficients were determined by minimizing the error between the calculated and experimental hydration free energies of 81 neutral organic molecules that have a variety of functional groups. The calculated hydration free energies agree well with the experimental results. The hydration free energy of any other solute molecule can then be calculated by summing the product of the linear combination coefficients and the basis functions for the solute.
提出了一种计算溶质周围空穴表面或溶剂体积中任意点的溶剂化自由能密度（SFED）的方法。在溶剂为水的特殊情况下，SFED被称为水合自由能密度（HFED）。HFED被描述为分子某些物理性质的函数。这些性质由简单的基函数表示。使用网格模型，通过在溶质周围的溶剂体积上对HFED进行积分来获得溶质的水合自由能。在引入的用于描述HFED的34个基函数中，只有6个对HFED有显著贡献。这些函数表示溶质的表面积和体积、溶质的极化和色散以及溶质与其环境之间的两种静电相互作用类型。HFED被描述为这些基函数的线性组合，通过计算溶质的每个原子与溶剂中的网格点之间的相互作用能之和来评估，其中每个网格点代表溶剂的有限体积。通过最小化81个具有各种官能团的中性有机分子的计算水合自由能与实验水合自由能之间的误差来确定线性组合系数。计算得到的水合自由能与实验结果吻合良好。然后，通过将线性组合系数与溶质的基函数的乘积相加，可以计算任何其他溶质分子的水合自由能。
