Outstanding Properties of the Hydration Shell around β-d-Glucose: A Computational Study

Area of Science:

• Computational Chemistry
• Physical Chemistry
• Biochemistry

Background:

• Understanding sugar-water interactions is crucial for explaining solubility differences.
• Simple sugars like glucose, mannose, and galactose are fundamental in biological systems.
• Ab initio molecular dynamics (AIMD) offers a quantum mechanical approach to study molecular behavior.

Purpose of the Study:

• To investigate the hydration properties of four simple sugars (α-d-glucose, β-d-glucose, α-d-mannose, α-d-galactose) in aqueous solution using AIMD.
• To correlate specific hydrogen bonding and electronic properties with observed differences in sugar solubility.
• To characterize the hydrophilic and hydrophobic hydration shells around the sugar molecules.

Main Methods:

• Ab initio molecular dynamics (AIMD) simulations of aqueous sugar solutions.
• Calculation of hydrogen bonding (HB) properties: number of donor/acceptor HBs, HB lengths, and strengths.
• Determination of electronic properties: water dipole moments and sugar oxygen partial charges.
• Characterization of hydration shells using spatial distribution functions.

Main Results:

• β-d-glucose forms the highest number of hydrophilic and the fewest hydrophobic connections to water molecules.
• The shortest average sugar-water hydrogen bond length was observed for β-d-glucose, indicating stronger interactions.
• β-d-glucose displayed distinct symmetry properties in its hydrophilic and hydrophobic hydration shells compared to other sugars.
• Calculated electronic properties, including water dipole moments and sugar oxygen partial charges, were analyzed.

Conclusions:

• Distinct hydration characteristics of β-d-glucose, including enhanced hydrophilic interactions and specific symmetry in hydration shells, correlate with its superior water solubility.
• These findings provide insights into the molecular basis of solubility differences among simple sugars.
• While these factors are important, other influences on solubility were not examined in this study.