Spectroscopic identification of interactions of Pb2+ with bovine serum albumin.

The effect of Pb(2+) targeted to bovine serum albumin (BSA) in vitro was investigated by fluorescence, synchronous fluorescence, UV absorption and circular dichroism (CD) spectrophotometry. The characteristic fluorescence of BSA was quenched, which indicated that Pb(2+) changed the skeleton of BSA and caused the gradual exposure of aromatic amino acid residues (Trp, Tyr, Phe) in the internal hydrophobic region of BSA. When the concentration of Pb(2+) was higher than 1 × 10(-4) mol/L, the BSA was completely denatured. The excess lead ion interacted with the aromatic amino acid residues of BSA exposed to the solution, which decreased the fluorescence of BSA further. According to the experiment results, we found that a lead-BSA complex was formed following static quenching and the binding site was calculated approximately equal to 1. This work reflected the interaction mechanism of BSA and Pb(2+) from the perspective of spectroscopy.