Long Range Structure and Zwitterion-Ion Interactions in Osmolyte Solutions

Cytosol composition not only dictates the osmotic balance of cells with their surroundings, but also determines the the range and nature of inter-protein interactions within the cell. While the role of salt in destabilising proteins is well known, the role that zwitterionic osmolytes play in these interactions is less clear. Here we will study model cytosol solutions of salt-zwitterion mixtures using neutron scattering. Recently we have investigated surface forces present in salt-zwitterion mixtures at an interface, and found periodic structure and long range screening forces that depend on sample composition. This experiment will investigate the occurrence of this structure in the bulk liquid, and its dependence on salt ion species. These results will have significant impact on our understanding of the role of zwitterionic osmolytes in maintaining protein structure and function.