Study on osmotic pressures for aqueous bovine serum albumin - NaCl solutions

The double - layer electric repulsion and dispersion attractive interactions between bovine serum albumin (BSA) molecules in aqueous NaCl solution are represented by a Yukawa potential and a Lennard-Jones potential, respectively, instead of the classical DLVO theory. Based on the osmotic McMillan - Mayer statistical theory, a new equation of state (EOS) is proposed in combination of a Yukawa EOS of Duh and Mier - Y - Teran with a perturbed IJ equation of Cotterman etc. to con-elate and predict the osmotic pressure data of aqueous BSA solution with NaCl. The result from the correlation of BSA in 0.15 mol/L NaCl aqueous solution can be used to predict the osmotic pressure of BSA in 1 similar to 5 mol/L aqueous NaCl solution. Two adjustable parameters (hard - sphere diameter sigma and IJ parameter epsilon /k) are used in this EOS with good con-elation and prediction results. A comparison with other theories is also discussed.