金属阳离子与β-肽骨架相互作用的振动光谱特征

Vibration Spectral Characteristics of Metal Cation andβ-Peptide Backbone Interaction

盐溶液中,金属阳离子(如Na+和Mg2+等)与肽分子骨架的相互作用,在酰胺基团的振动光谱中能得到体现。本工作利用红外光谱实验、分子动力学模拟和量化计算方法,以酰胺-Ⅰ带和酰胺-Ⅱ带为探针,研究了上述金属阳离子与?-肽模型分子-氮乙基丙酰胺(N-ethylpropionamide,NEPA)分子骨架的作用。研究表明在盐溶液中,阳离子/阴离子/水分子之间形成复合物。作为阳离子配体的水分子与NEPA中的羰基氧之间存在动态相互作用,从而使得酰胺-Ⅰ带和酰胺-Ⅱ带的光谱发生劈裂。我们也讨论了酰胺NH与水合离子团簇的相互作用。

The interaction between metal cation and peptide backbone can be reflected in infrared spectroscopy.In this work,FTIR spectroscopy,molecular dynamics simulations and quantum chemical calculations were carried out to examine the metal cation effect on the amide-Ⅰ and amide-Ⅱ modes in a modelβ-peptide,N-ethylpropionamide(NEPA).Monovalent(Na+)and divalent(Mg2+)metal cations were chosen.Our results showed that in saline solution,NEPA,metal cations,anions and water form a dynamical complex.The amide-Ⅰ and amide-Ⅱ modes of NEPA showed sensitivity to the configuration of the complex via the amide O atom in the form of peak splitting.The interaction between amide NH and hydrated ionic clusters was also discussed.