Physicochemical properties of structured water in human albumin and gammaglobulin solutions

Abstract The physicochemical properties of the different phases of water molecules were studied in concentrated solutions (132 g/L) of human serum albumin and gammaglobulin by 1 H NMR relaxometry. Spin-lattice (T1) relaxation times of total water and structured water (non-freezable water) were measured at 40 MHz above and below the freezing point of bulk water (ordinary, liquid water) at different temperatures. Analysis of the temperature dependence of the T1 demonstrated that total water differed qualitatively while structured water characteristics changed both quantitatively and qualitatively in the two protein solutions. Comparison of the temperature dependence of the structured water’s T1 in the two solutions in the presence of an increasing concentration of manganese chloride allowed two main conclusions to be drawn. Firstly, the differences observed in total water and structured water physicochemical properties are directly related to protein structure and three-dimensional arrangement. Secondly, the motion of structured water determines the motion of the total water in the system through the values of the translational diffusion and chemical exchange correlation times τ D and τm.