Biomolecular structure and dynamics

The interaction of water with proteins with respect to their structure and function is a recently emerging field. We have recently studied water around DNA, proteins and biopolymers using various neutron sources around the world. These studies have shed new light towards the understanding of the structure and dynamics of water in the biological environments. In order to make further progress in this field, we have recently concentrated our efforts on the basic building block of proteins - amino acids - using inelastic and quasi-elastic neutron scattering techniques and computational methods (molecular dynamics and ab initio quantum mechanics).

Inelastic neutron scattering of hydrogen bonding in ices is of considerable relevance to a range of disciplines where water is considered to be important. It not only provides the foundation for us to understand a range of thermodynamical properties of ices and associated anomalies (e.g. providing the basic experimental information for theoretical modelling, e.g. ab initio quantum chemistry calculations, molecular and lattice dynamical calculations for ice and water), but also equally important for us to understand the role (or interaction) of water around biological systems.

However, the complex structures of DNA/proteins and the conformational arrangements of water molecules around them make it very hard to gain a clear picture of the spatial arrangements, as often only averaged (time and molecule) positions are given. In addition, neutron fluxes are typically weak compared to X-ray sources and this necessitates both long collection times and extremely large crystals. However, using vibrational spectroscopy (including neutron, IR and Raman), we can determine the local structures of water in biological environments by comparing the spectra of known structures, such as exotic phases of ice with those in biological systems. We can thus deduce the interactions between water molecules and DNA/proteins.

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