Experimental study on the interaction between lead and serum albumin

The interaction between lead (Pb 2+) and bovine serum albumin (BSA) was studied in the temperature range of 10-40 °C through metal-titration experiments under equilibrium conditions. Lead binding to BSA was monitored by measuring the intensity changes in the difference absorption band at 243 nm following the addition of increasing amounts of lead ions to an aqueous solution at constant protein concentration (2.5 × 10 -5 M). The equilibrium binding data were found to be well described by a Langmuir-type equation, with an almost temperature-independent saturation value. According to the estimated δH 0 and δS 0, the binding of Pb 2+ to BSA was both enthalpy-driven and entropy-driven, with the entropic contribution providing the major driving force. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd.