Infrared spectrum analysis of the dissociated states of simple amino acids
Infrared spectrum analysis of the dissociated states of simple amino acids
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DOI：
10.1016/j.saa.2014.05.026
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发表时间：
2014-11-11
影响因子：
4.4
通讯作者：
Pendleton, Phillip
中科院分区：
文献类型：
--
作者：
Sebben, Damien;Pendleton, Phillip
在这项工作中，我们提出了详细的分析，在范围1 < pH < 12的甘氨酸和赖氨酸的稀水溶液的解离。使用适当的光谱减法方法，我们获得了溶剂化物种的ATR-IR光谱作为pH值的函数。在1800和1100 cm（-1）之间的吸收区域内，离子物种的可辨别的变化被确定。通过将峰去卷积技术应用于光谱，我们正确地解释了从1615到1600 cm-1的表观峰位移是由于在出现COO-不对称拉伸的同时后退的NH 3+不对称变形。在10和100 mmol/L NaCl条件下，研究了水溶液环境对该反应的影响。还从每个溶液相光谱中减去每个pH下的盐溶液光谱。在pH < 4.5的范围内分析C=O和COO-的去卷积峰面积，在pH > 8的范围内分析NH 2和NH3+的去卷积峰面积，得到氨基酸的一致pK（a）值。(C)2014爱思唯尔有限公司版权所有。
In this work, we present detailed analyses of the dissociation of dilute aqueous solutions of glycine and of lysine over the range 1 < pH < 12. Using appropriate spectrum subtraction methods, we obtained ATR-IR spectra of the solvated species as a function of pH. Discernible changes in the ionic species were identified in the absorption region between 1800 and 1100 cm(-1). By applying peak deconvolution techniques to the spectra, we correctly interpret the apparent peak shift from 1615 to 1600 cm-1 as being due to the receding NH3+ asymmetric deformation alongside the appearing COO- asymmetric stretching. The effect of aqueous solution environment was also investigated in terms of 10 and 100 mmol/L NaCl. Salt solution spectra at each pH were also subtracted from each solution phase spectrum. Analysis of the deconvoluted peak areas due to C=O and COO- at pH ranges < 4.5 and those due to NH2 and NH3+ for pH > 8 resulted in consistent pK(a) values for the amino acids. (C) 2014 Elsevier B.V. All rights reserved.