Department of Chemistry, 213 CBC Building, Kansas State University, Manhattan, KS 66506-0401, USA.
Phys Chem Chem Phys. 2011 Oct 28;13(40):18154-67. doi: 10.1039/c1cp21883b. Epub 2011 Sep 19.
In a continuation of our efforts to develop a united atom non-polarizable protein force field based upon the solution theory of Kirkwood and Buff i.e., the Kirkwood-Buff Force Field (KBFF) approach, we present KBFF models for the side chains of phenylalanine, tyrosine, tryptophan, and histidine, including both tautomers of neutral histidine and doubly-protonated histidine. The force fields were specifically designed to reproduce the thermodynamic properties of mixtures over the full composition range in an attempt to provide an improved description of intermolecular interactions. The models were developed by careful parameterization of the solution phase partial charges to reproduce the experimental Kirkwood-Buff integrals for mixtures of solutes representative of the amino acid sidechains in solution. The KBFF parameters and simulated thermodynamic and structural properties are presented for the following eleven binary mixtures: benzene + methanol, benzene + toluene, toluene + methanol, toluene + phenol, toluene + p-cresol, pyrrole + methanol, indole + methanol, pyridine + methanol, pyridine + water, histidine + water, and histidine hydrochloride + water. It is argued that the present approach and models provide a reasonable description of intermolecular interactions which ensures that the required balance between solute-solute, solute-solvent, and solvent-solvent distributions is obtained.
在继续努力开发基于 Kirkwood 和 Buff 溶液理论的统一原子非极化蛋白质力场（即 Kirkwood-Buff 力场（KBFF）方法）的过程中，我们提出了苯丙氨酸、酪氨酸、色氨酸和组氨酸侧链的 KBFF 模型，包括中性组氨酸和双质子化组氨酸的两种互变异构体。这些力场是专门设计用来重现混合物在全组成范围内的热力学性质，试图提供对分子间相互作用的改进描述。该模型是通过仔细参数化溶液相部分电荷来开发的，以重现代表溶液中氨基酸侧链的溶质混合物的实验 Kirkwood-Buff 积分。为以下十一种二元混合物提供了 KBFF 参数和模拟热力学和结构性质：苯+甲醇、苯+甲苯、甲苯+甲醇、甲苯+苯酚、甲苯+p-甲酚、吡咯+甲醇、吲哚+甲醇、吡啶+甲醇、吡啶+水、组氨酸+水和组氨酸盐酸盐+水。有人认为，目前的方法和模型提供了对分子间相互作用的合理描述，确保了在溶质-溶质、溶质-溶剂和溶剂-溶剂分布之间获得所需的平衡。
