Investigation on Binding between Cations and Amides using UV Raman Spectroscopy

基于紫外拉曼光谱的阳离子与酰胺相互作用研究

The interaction of proteins with salt ions plays an important role in life activities.We used butyramide as a model molecule to investigate the interaction of protein backbones with cations.The experiment was performed in an aqueous solution of metal chloride using UV Raman spectroscopy.It was found that well-hydrated metal cations(Ca^(2+),Mg^(2+))tend to bind to C=O in the amide bond,resulting in redistribution of the amide I band peaks.Specifically,the peak intensity ratio of 1655 cm^(-1)to 1610 cm^(-1)increases significantly with increasing concentrations.However,this phenomenon is not obviously observed in NaCl solution.Furthermore,we studied the effect of salt ions on the water structures.The addition of Ca^(2+)and Mg^(2+)is beneficial to the enhancement of the water signal at the 3400 cm^(-1)position,while the Na^(+)at the same concentration is not obvious.The results have shown that the interaction between cations and amides satisfies the following order:Ca^(2+)>Mg^(2+)>Na^(+),which conforms to the Hofmeister series.

蛋白质与盐离子的相互作用在生命活动中起着重要作用。本文使用丁酰胺作为模型分子,通过紫外拉曼光谱观察丁酰胺与金属氯化物水溶液的结合,研究蛋白质骨架与阳离子的相互作用.发现了水合良好的金属阳离子(Ca^(2+),Mg^(2+))倾向于结合酰胺键中与C=O,从而使得酰胺I谱带进行重新分配.具体而言,1655cm^(-1)处与1610cm^(-1)处的峰强度比值随浓度的增加而显著增加,此现象在NaCl溶液中并未明显观察到.本文还研究了盐离子对水结构的影响,Ca^(2+)和Mg^(2+)的加入有利于水在3400 cm^(-1)位置的信号增强,而相同浓度下的Na^(+)则不明显.研究表明,阳离子与酰胺的相互作用满足以下顺序:Ca^(2+)>Mg^(2+)>Na^(+),符合霍夫迈斯特序列.