Study of thermally and chemically unfolded conformations of bovine serum albumin by means of dynamic light scattering

The change of conformation of a bovine serum albumin (BSA) has been characterized using dynamic light scattering (DLS). Structural properties were investigated as a function of chemical denaturant concentrations and a temperature. In pure water, the protein keeps its native size at guanidine hydrochloride (GdmCl) concentrations below 1 M and behaves like an excluded volume chain above 4 M. A transition in structure and properties of the protein seems to occur around a GdmCl concentration of 1.7 M. Still, this protein forms an unfolded conformation in presence of 6 M of urea concentration and the value of the diffusive virial coefficient indicates that the interactions between the polypeptide chain and solvent are repulsive. The true value of the Tm = 43 °C, has obtained by linear extrapolation to 0 M GdmCl.