Chemistry Department, United States Naval Academy, 572 Holloway Road, Annapolis, Maryland 21402, USA.
J Phys Chem A. 2012 Feb 9;116(5):1396-408. doi: 10.1021/jp206152d. Epub 2012 Jan 27.
A computational study of the conformational preferences of the glycine tripeptide analog, Ac-Gly-Gly-NHMe, has been carried out. The molecule is considered in isolation as well as with a continuum model of aqueous solvation. In the absence of solvent, several low-energy conformers are found that exhibit turnlike structures including type I and type II β turns. Upon consideration of aqueous solvation, two conformers, corresponding to the type I and II turn structures are found to be significantly lower in energy than all others. Results from ab initio molecular orbital theory calculations at MP2/aug-cc-pVTZ//MP2/6-311+G(d,p) are compared with those from density functional theory with B3LYP, ωB97X-D, B97-D, and M06-2X as well as several empirical force fields.
已对甘氨酰甘氨酰氨甲基乙酸三肽类似物的构象偏好进行了计算研究。该分子在没有溶剂的情况下被单独考虑，以及在水溶剂化的连续模型下被考虑。在没有溶剂的情况下，发现了几个低能量构象，它们表现出包括 I 型和 II 型β转角在内的转折结构。在考虑水溶剂化时，发现两种构象，对应于 I 型和 II 型转折结构，其能量明显低于其他所有构象。在 MP2/aug-cc-pVTZ//MP2/6-311+G(d,p)水平上的从头算分子轨道理论计算结果与密度泛函理论（包括 B3LYP、ωB97X-D、B97-D 和 M06-2X 以及几种经验力场）的结果进行了比较。
