SANS Study of Liquid‐Liquid Phase Transition in Protein Electrolyte Solution

Small‐angle Neutron Scattering (SANS) measurements have been performed on lysozyme protein solution to examine liquid‐liquid phase transition with the addition of NaCl. We show that the liquid‐liquid phase transition is governed by the increase in the attractive interaction between protein molecules as tuned by the salt concentration. This attractive interaction is modeled by the Baxter’s sticky hard sphere potential. It is found that when the attractive potential becomes significantly larger than the thermal energy protein molecules coalesce to form gel.