CALORIMETRIC STUDY OF HUMAN SERUM-ALBUMIN IN WATER DIOXANE MIXTURES

The calorimetric isotherm of water sorption by solid human serum albumin (HSA) was measured in water-dioxane mixtures. This isotherm has been successfully described at low water contents in the solvent within the framework of the presented model. The adsorption equilibrium constant and the monolayer formation energy were estimated from this model. The interaction enthalpies of solid HSA with the solvent in water-rich mixtures do not differ essentially from the solution enthalpy of HSA in water. This means that the solvent water content may be sufficient for the intermolecular interactions of HSA suspended in a water-organic mixture to be similar to those in aqueous protein solution.