Microcalorimetric, volumetric and dynamic light scattering studies on nucleating ovalbumin solutions

Isothermal titration microcalorimetry, densimetry and dynamic light scattering (DLS) have been employed to investigate the behavior of nucleating ovalbumin solutions when varying the concentration of (NH4)2SO4 from 0.8 to 2.2 M. Concentrations of the ovalbumin were kept in the narrow range from 0.12 to 0.17 mM. Calorimetric results show the dependence of the heat effect on ammonium sulfate concentration with the biggest negative heat effect around 1.5 mol/kg concentration. Volumetric data indicate that apparent molar volume of ovalbumin exhibits a maximum at around 1.6 mol/kg concentration of ammonium sulfate. DLS experiment allowed to determine the aggregation kinetics and the size of the aggregates formed by ovalbumin in different ammonium sulfate concentrations.