Sugars in the gas phase.: Spectroscopy, conformation, hydration, co-operativity and selectivity

The functional importance of carbohydrates in biological processes, particularly those involving specific molecular recognition, is immense. Characterizing the three-dimensional structures of carbohydrates and glycoconjugates and their interactions with other molecules, particularly the ubiquitous solvent, water, are key starting points on the road towards the understanding of these processes. The review introduces a new strategy, combining electronic and vibrational spectroscopy of mass-selected carbohydrate molecules and their hydrated ( and also protonated) complexes, conducted under molecular beam conditions, with ab initio computation. Its early successes have revealed a uniquely powerful means of characterizing carbohydrate conformations and hydrated structures, the hydrogen-bonded networks they support ( or which support them) and the specificity of their interactions with other molecules. The new information, obtained in the gas phase, complements that provided by more 'traditional' condensed phase methods such as NMR, X-ray diffraction, molecular mechanics and molecular dynamics calculations. The review concludes with a vision of the challenges and opportunities offered by applications of molecular beam spectroscopy and their relevance in a biological context.