A DSC study of zinc binding to bovine serum albumin (BSA)

The thermal denaturation of bovine serum albumin (BSA) is a kinetically and thermodynamically controlled process. The effects of zinc binding to bovine se- rum albumin (BSA), followed by differential scanning calorimetry (DSC), were in- vestigated in this work, with the purpose of obtaining a better understanding of the albumin/zinc interaction. From the DSC curves, the thermodynamic parameters of protein denaturation were obtained, i.e., the temperature of thermal transition maxi- mum (Tm), calorimetric enthalpy (H cal ), van't Hoff enthalpy (H vH ), the number of binding sites (I, II), the binding constants for each binding site (KbI, KbII )a nd the av- erage number of ligands bound per mole of native protein XN. The thermodynamic data of protein unfolding showed that zinc binding to bovine serum albumin in- creases the stability of the protein (higher values of H cal ) and the different ratio H cal /H vH indicates the perturbation of the protein during thermal denaturation.