Silva Weslley G D P, Tormena Cláudio F, Rittner Roberto
Chemistry Institute , University of Campinas , Campinas , São Paulo 13083-970 , Brazil.
Department of Chemistry , University of Manitoba , Winnipeg , Manitoba R3T 2N2 , Canada.
J Phys Chem A. 2018 May 10;122(18):4555-4561. doi: 10.1021/acs.jpca.8b02523. Epub 2018 Apr 25.
The conformational preferences of proteinogenic glutamic acid esterified (GluOMe) and N-acetylated (AcGluOMe) derivatives have been determined in solution for the first time. Theoretical calculations at the ωB97X-D/aug-cc-pVTZ made possible the assignment of six and eight stable conformers for GluOMe and AcGluOMe, respectively. The conformational equilibrium of the studied compounds was evaluated in different organic solvents using a combination of the integral equation formalism polarizable continuum model (IEF-PCM) and H NMR spectroscopy data. The results showed that the conformational equilibrium of both derivatives change in the presence of solvent. According to the quantum theory of atoms in molecules (QTAIM), non-covalent interactions (NCI), and natural bond orbitals (NBO) analyses, the conformational preferences observed for GluOMe and AcGluOMe are not dictated by the presence of a specific interaction but are due to a combination of hyperconjugative and steric effects.
首次在溶液中确定了蛋白质原性谷氨酸酯化（GluOMe）和N-乙酰化（AcGluOMe）衍生物的构象偏好。在ωB97X-D/aug-cc-pVTZ水平上的理论计算分别为GluOMe和AcGluOMe确定了六个和八个稳定构象。使用积分方程形式极化连续介质模型（IEF-PCM）和1H NMR光谱数据相结合的方法，在不同有机溶剂中评估了所研究化合物的构象平衡。结果表明，两种衍生物的构象平衡在溶剂存在下会发生变化。根据分子中的原子量子理论（QTAIM）、非共价相互作用（NCI）和自然键轨道（NBO）分析，观察到的GluOMe和AcGluOMe的构象偏好不是由特定相互作用的存在决定的，而是超共轭和空间效应共同作用的结果。
