The Effect of Salts for Osmotic Pressure of Aqueous Protein Solutions :Ovalbumin/Salt and Bovine Serum Albumin(BSA)/Salt Solutions

Abstract

Osmotic pressure, the important property in the interpretation of biophysical systems, is determined from various conditions. Especially in an aqueous protein solutions, the osmotic pressure can be used to characterize interactions between globular protein and salt molecules. In the meanwhile, the method for experimentally determining cloud-point curves of liquid protein solution is provided by thermo-optical analysis(TOA). The cloud-point temperature(CPT) is measured as functions of salt's type and concentration at constant pH for ovalbumin/salt and bovine serum albumin(BSA)/salt solutions. The interaction energy between various protein's surface of amino acid sequence and salt's ion is contributed to the osmotic pressure. The energy parameter expressed as a function of ionic strength is obtained from CPT data in the equation of state based on liquid-liquid equilibrium conditions and used to describe the osmotic pressure through relatively simple thermodynamic model.