Static and Dynamic Study of Disaccharides Trehalose, Maltose and Sucrose (original) (raw)

Structural Chemistry, 2016

Abstract

In this work, electronic structure calculations and Molecular Dynamics (MD) simulations were performed in order to carry out a static and dynamic study of disaccharides, trehalose, sucrose and maltose. These three disaccharides share the same chemical formula and the same number of OH groups; however, it has been widely shown that trehalose has a superior ability to protect biological structures. In order to contribute to the understanding of the factors that determine this ability of trehalose, in this work a comparative study of the three disaccharides in gas phase and dilute aqueous solution is performed. A detailed analysis of hydrogen bonds (HBs) was carried out using Quantum Theory of Atoms In Molecules (QTAIM) on wave functions obtained at B3LYP/6-311++G** level. Besides, stereoelectronic effects were examined by Natural Bond Orbital (NBO) analysis. In addition, the intra- and intermolecular HB interactions in MD runs of infinitely dilute aqueous solution of sugars have been monitored. Results show that the three disaccharides form a significant number of HBs of C-H∙∙∙O type, mainly in trehalose. An intermolecular bond of this type determines the conformational rigidity of trehalose in solution which contributes to stabilize a clam shell conformation as the one observed in the crystal. In this disaccharide, hydrogen bonds are more labile, showing a quickly exchange of the water molecules that form these HBs. This fact slows down ice formation and could be the explanation for trehalose capabilities as a cryoprotectant.

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