Conformational study of cationic, zwitterionic, anionic species of aspartic acid, water-added forms and their protonation. A DFT method

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• 作者：Wichien Sang-aroon and Vithaya Ruangpornvisuti
• 关键词：Aspartic acid ; Cationic ; Zwitterionic ; Anionic species ; Conformation ; DFT ; Protonation
• 刊名：Journal of Molecular Structure ; THEOCHEM
• 出版年：2006
• 期刊代码：63_01661280
• 类别：ch
• 出版时间：31 January 2006
• 卷：758
• 期：2-3
• 页码：181-187
• 文件大小：261 K

摘要

The potential energy surfaces of various species of aspartic acid have been computed at the DFT/B3LYP/6-31G(d) level of theory. Conformations of 34, 11, 9 and 3 were found from 324, 162, 81 and 81 possible conformers for species H₃asp⁺, H₂asp, Hasp⁻ and asp²⁻, respectively. The most stable conformation for species H₃asp⁺, H₂asp, Hasp⁻ and asp²⁻ are γ_D, α_L, ε_L and β_L conformers, respectively. Three protonation steps due to the tetrahydrated forms of species asp²⁻, Hasp⁻ and H₂asp of aspartic acid computed at the B3LYP/6-31+G(d, p) level of theory with zero-point vibrational energy corrections are exothermic reactions and their stabilization energies of the stepwise protonation are −244.68, −308.57 and −379.97 kcal mol⁻¹, respectively.