Dielectric study of the denaturation process in albumin-urea solutions

The dielectric relaxation of bovine serum albumin (BSA) aqueous solution was studied in various stages of urea denaturation, by means of the Thermally Stimulated Depolarization Currents (TSDC) technique. A large variation of urea concentration was utilized (0 to 4 M). Special attention was given to concentrations 0.006 and 0.046 M which are comparable to the ones measured in normal and uremic human serum. Three spectral bands were recorded in the temperature range 77 to 300 K which are attributed to the reorientation mechanisms of bulk and hydration water and protein macromolecules. The activation energies for all three mechanisms appear to be dependent on urea concentration and this result is discussed in terms of the conformational changes of albumin upon denaturation