Conformational change and selectivity in explicitly hydrated carbohydrates

The combination of vibrational spectroscopy, conducted in a supersonic jet expansion, with computation through molecular mechanics, density functional theory (DFT) and ab initio calculation, has provided a new approach to the conformational and structural assignment of carbohydrates and their molecular complexes. This article reviews the new insights it has provided on the regioselectivity and conformational choice in singly and multiply hydrated monosaccharides. It reveals a systematic pattern of conformational preference and binding site selectivity, driven by the provision of optimal, co-operative hydrogen-bonded networks in the hydrated sugars. Water binding is invariably 'focused' around the hydroxymethyl group (when present); the bound water molecules (on multiply hydrated mannose) are located exclusively on its hydrophilic face while the hydrophobic face remains 'dry'; and there is a correlation between the locale of the preferred binding sites and those involved in protein-carbohydrate molecular recognition.