Effect of water on physical transitions of human serum albumin

Differential thermal analysis is performed for native human serum albumin, denatured human serum albumin, and their mixtures with water in the range 80–550 K. The temperatures of phase transitions of the protein are determined, and the effect of water on these transitions is ascertained. The limit of water solubility in the native protein is estimated from the calorimetry data on the enthalpy of melting of the excess-water phase. The phase diagram of the albumin-water system is plotted and analyzed in wide temperature and concentration ranges.