As a common heavy metal, Pb (II) can react with biological macromolecules in the human body and have an impact on human health, but there are few studies on its synergistic interaction with a variety of proteins of different abundance. Pb (II) binding with a synthetic model protein system (bovine serum albumin (BSA) and bovine lactoferrin (BLF)) was characterized using fluorescence spectroscopy and was described using a quantitative model. Pb (II) quenched the fluorescence of BSA-BLF, indicating that Pb (II) interacted with the BSA-BLF protein system, and was affected by single protein, mixed proteins and the solution microenvironment. A model was constructed and an indicator of the interaction (FPI) was derived to quantify the interactions. There was a high correlation (R2=0.9182, p<0.001) between the FPI and the Pb (II) concentration when the interaction models were analyzed with a Taylor function. The effects of the solvent microenvironment on BSA, BLF and BSA-BLF were evaluated using the IOM (overall microenvironmental influence factor). BLF was more easily affected by the solution microenvironment with increasing concentrations than BSA, while BSA-BLF was less affected.

Luwei Tian, Ming Guo, Xingtao Xu and Linfang Shi