Seminars Archive

Bio-molecules hydration dynamic studied by UV Raman spectroscopy

Abstract
The understanding of hydration in biomolecules is a challenge that is requiring tremendous theoretical and experimental efforts to the scientific community. Raman spectroscopy is potentially a very useful tool to investigate the hydration mechanism. The recent construction of an ultraviolet Raman spectrometer at the IUVS beamline at Elettra-Sincrotrone Trieste allows carrying out experiments in both resonant and non-resonant conditions. The low fluorescent signal in the ultraviolet energy range, the high resolution (namely below 1 cm-1) and the possibility to enhance the cross section exploiting electronic transitions make the instrument particularly suited to study organic solutions. We exploited the instrument to study a variety of systems ranging from simple amino acids to more complex systems including DNA. In this presentation we will point out how the use of ultraviolet radiation can help to get a deeper understanding of the hydration shell formation mechanism in prototypical samples like Acetamide, Acetic Acid and Glycine. We demonstrated that below a crossover temperature of about 60o C the hydrogen bonds of water in proximity of the hydrophobic groups become stiffer. Studies at room temperature as a function of the solute content demonstrate that the hydrogen bonds of water with carbonyl groups show an increase of lifetime up to the second hydration shell formation. These experimental results pave the way to the use of the proposed approach to investigate more complex structural changes, such e.g. the protein folding.