Effect of water on the temperatures of human immunoglobulin conformation transitions

A differential thermal analysis of native and denaturated human immunoglobulin (G isotype) and mixtures of the native protein with water over the temperature range of 80–570 K is conducted. Temperatures of the protein conformational transitions and the effect of water on them are investigated. The limit of water solubility in the native protein is determined calorimetrically from the enthalpy of excess water phase melting. A physical state diagram of the immunoglobulin-water system over a wide range of temperatures and component concentrations is built and analyzed.