Effect of ethanol, ammonium sulfate, fatty acids, and temperature on the solution behavior of bovine serum albumin.

Ternary phase diagrams (TPDs) for aqueous bovine serum albumin (BSA) solutions containing ethanol or (NH4)2SO4 were determined for temperatures ranging from 20 to 70 degrees C. At 20 degrees C, ethanol destabilized BSA, resulting in gel formation at moderate solute concentrations. In contrast, (NH4)2SO4 concentrations above 20 wt % precipitated BSA from solution. Raising the temperature led to gel formation at increasingly lower BSA and solute concentrations. The removal of adsorbed fatty acids from BSA had little effect on the ethanol TPDs but reduced protein solubility in (NH4)2SO4. Moreover, the salt TPDs of fatty-acid-poor BSA were similar to those previously observed with S-ovalbumin.