Interaction of trehalose with water and protein for the understanding of biological stabilization

Licentiate thesis, 2016

The understanding of biomolecular interactions with water and co-solutes opens up further understanding for the mechanism behind biomolecular stabilization. This is highly important for developing technologies aimed to preserve biological material. Such techniques include cryopreservation of for example pharmaceuticals or human organ transplants. For these purposes, the disaccharide trehalose has been shown to be an outstanding stabilizing agent during cryostorage or storage of desiccated materials. However, the stabilizing role of trehalose is still not fully understood; why does trehalose perform better than other molecules? To partly answer this question, this work investigated two important molecular systems. First, the structural properties of aqueous trehalose were studied using neutron diffraction combined with EPSR modeling. Secondly, ternary protein–trehalose–water systems were investigated using calorimetric experiments to obtain indirect evidence for different structural properties. The aqueous trehalose study provided a direct proof of strong trehalose–water interactions, and consequently a strong perturbation of the bulk-water structure. Furthermore, this study found that the trehalose molecules are highly unlikely to cluster to each other, which is hypothesized to be the reason for why trehalose is able to interact so strongly with water. The results from the calorimetric study gave support to the preferential hydration model. This study also showed that the protein stability is not necessarily coupled to the glass transition temperature of the trehalose–protein–water-matrix.