Forsting Thomas, Gottschalk Hannes C, Hartwig Beppo, Mons Michel, Suhm Martin A
Institut für Physikalische Chemie, Universität Göttingen, Tammannstr. 6, 37077 Göttingen, Germany.
Phys Chem Chem Phys. 2017 May 3;19(17):10727-10737. doi: 10.1039/c6cp07989j.
The dimer of trans-N-methylacetamide serves as a simple model for hydrogen bonds in peptides, free of any backbone distortions. Its preferred structures represent benchmark systems for an accurate quantum chemical description of protein interactions. The trimer allows for either two linear or three strained hydrogen bonds, with the former being the only structural motif considered so far in the literature, but the latter winning in energy by a large margin due to London dispersion. A combination of linear Raman and infrared supersonic jet techniques with B3LYP-D3/aug-cc-pVTZ quantum chemical predictions corrects earlier tentative spectroscopic assignments based on a hybrid density functional without dispersion correction. Linear Amide I-III infrared spectra of the jet-cooled monomer are compared to those recently obtained by action spectroscopy.
反式-N-甲基乙酰胺二聚体作为肽中氢键的简单模型，不存在任何主链扭曲。其优选结构代表了用于精确量子化学描述蛋白质相互作用的基准系统。三聚体允许形成两个线性氢键或三个应变氢键，前者是迄今为止文献中唯一考虑的结构基序，但由于伦敦色散作用，后者在能量上大幅胜出。将线性拉曼和红外超音速喷射技术与B3LYP-D3/aug-cc-pVTZ量子化学预测相结合，纠正了早期基于无色散校正的混合密度泛函的初步光谱归属。将喷射冷却单体的线性酰胺I-III红外光谱与最近通过光解光谱获得的光谱进行了比较。
