Serine in aqueous solutions at different pH: Conformational preferences and vibrational spectra of cationic, anionic and zwitterionic species

The aim of this study is to understand the conformational preferences of l-Serine (C₃H₇NO₃, 2-amino-3-hydroxypropanoic acid) at different pH conditions. A conformational study in aqueous solution of the dissociation equilibrium of the polar amino acid l-Serine, was carried out for this purpose. We r...

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Bibliographic Details
Published in:Journal of molecular structure 2013, Vol.1046, p.136-146
Main Authors: Quesada-Moreno, M. Mar, Avilés-Moreno, Juan Ramón, Márquez-García, Ana África, Partal-Ureña, Francisco, López González, Juan Jesús
Format: Article
Language:English
Subjects:
amino acids
aqueous solutions
dissociation
landscapes
temperature
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Summary:The aim of this study is to understand the conformational preferences of l-Serine (C₃H₇NO₃, 2-amino-3-hydroxypropanoic acid) at different pH conditions. A conformational study in aqueous solution of the dissociation equilibrium of the polar amino acid l-Serine, was carried out for this purpose. We recorded, at room temperature, the Mid-IR, FarIR and Raman spectra of l-Serine from the aqueous solutions at pH values 5.82 (zwitterionic species), 1.00 (protonated species) and 13.00 (deprotonated species). Both the study of the conformational landscape and the theoretical analysis of the vibrational features were done using DFT and ab initio calculations, i.e. B3LYP/6-31+G(d,p), M062X/6-31+G(d,p) and MP2/6-31+G(d,p) levels of theory. The presence of water was included with the IEF-PCM implicit hydration model. Concerning the zwitterion, analysis of the low frequency region (700–50cm⁻¹) in the FT-Raman and FarIR spectra reveals important information for assignment of the most stable structures.
ISSN:0022-2860
1872-8014