Influence of the Anomeric Conformation in the Intermolecular Interactions of Glucose

Carbohydrates are, together with amino acids, DNA bases, and lipids, the building blocks of living beings. They play a central role in basic functions such as immunity and signaling, which are governed by noncovalent interactions between sugar units and other biomolecules. To get insights into such interactions between monosaccharide units, we used a combination of mass-resolved laser spectroscopy in supersonic expansions and molecular structure calculations. The results obtained clearly demonstrate that the small stability difference between the alpha/beta anomers of glucopyranose derivatives is reversed and amplified during molecular aggregation, making the complexes of the beta-anomers significantly more stable. The amplification mechanism seems to be formation of extensive hydrogen-bond networks extending through the two interacting molecules. The same mechanism must be at play in the interactions of biological and synthetic receptors with glycans, which exhibit, in general, a higher affinity for a specific anomer, usually the beta anomer.