Relationships between Molecular Structure of Carbohydrates and Their Dynamic Hydration Shells Revealed by Terahertz Time-Domain Spectroscopy

Abstract

Despite more than a century of research on the hydration of biomolecules, the hydration of carbohydrates is insufficiently studied. An approach to studying dynamic hydration shells of carbohydrates in aqueous solutions based on terahertz time-domain spectroscopy assay is developed in the current work. Monosaccharides (glucose, galactose, galacturonic acid) and polysaccharides (dextran, amylopectin, polygalacturonic acid) solutions were studied. The contribution of the dissolved carbohydrates was subtracted from the measured dielectric permittivities of aqueous solutions based on the corresponding effective medium models. The obtained dielectric permittivities of the water phase were used to calculate the parameters describing intermolecular relaxation and oscillatory processes in water. It is established that all of the analyzed carbohydrates lead to the increase of the binding degree of water. Hydration shells of monosaccharides are characterized by elevated numbers of hydrogen bonds and their mean energies compared to undisturbed water, as well as by elevated numbers and the lifetime of free water molecules. The axial orientation of the OH(4) group of sugar facilitates a wider distribution of hydrogen bond energies in hydration shells compared to equatorial orientation. The presence of the carboxylic group affects water structure significantly. The hydration of polysaccharides is less apparent than that of monosaccharides, and it depends on the type of glycosidic bonds.

Application of Terahertz Time-Domain Spectroscopy to Study the Microheterogeneities of Solutions: A Case Study of Aqueous Sugar Solutions

“…It is sensitive not only to the primary strongly bound hydrate shell but also to more distant areas of hydration with altered dynamics of water molecules [33][34][35]. In our previous work, we analyzed solutions of proteins [36], phospholipids [35], nucleic acids [37,38], and sugars [39] using the THz time-domain spectroscopy (THz-TDS) method, which confirms the great possibilities of this method in the study of hydration. Also, in a recent work [40] on the study of aqueous solutions of alcohols by THz spectroscopy, it was shown that this method is very informative in the analysis of intermolecular hydrogen bonds and molecular micro-inhomogeneities.…”

“…In this case, all three permittivities are complex functions of frequency, i.e., DS. We used a similar approach to separating the dielectric contributions of phases for sugar solutions earlier [39].…”

From Lactose to Alkyl Galactoside Fatty Acid Esters as Non‐Ionic Biosurfactants: A Two‐Step Enzymatic Approach to Cheese Whey Valorization

“…These results could be explained by looking into the chemical structures: 17 and SER compounds are epimers in the C‐4 position, being the orientation of the OH(4) group the only difference. According to the literature, [50] this behavior is strictly connected to a different ability of matching the tetrahedral hydrogen bond network of water. Sugars with an axial OH(4) group, such as galactose, match the three‐dimensional water structure much worse than sugars with an equatorially‐oriented OH(4), as in the case of glucose.…”

Regulating Antifreeze Activity through Water: Latent Functions of the Sugars of Antifreeze Glycoprotein Revealed by Total Chemical Synthesis

“…This may arise from the intrinsic geometry of the hydroxy groups of GalNAc and GlcNAc. The water molecules directly bound on sugars potentially restructure surrounding water molecules mediating between the first hydration shell and bulk water [14] . The water molecules in this interfacial water phase between sugar and bulk water phase are orientationally disordered compared with the bulk water (Figure 7).…”