The binding affinity of phthalate plasticizers-protein revealed by spectroscopic techniques and molecular modeling

Phthalate plasticizers have been subjected to close scrutiny and evidences of their toxicity and other negative environmental impacts have arisen as a result of their use in food in some countries. Once entering human body, plasticizers could affect the conformation of human serum albumin and protein function. The interaction between two phthalate plasticizers and human serum albumin was investigated by multispectroscopic techniques and molecular modeling. The alteration in protein conformational stability was determined by fluorescence quenching data. The thermodynamic parameters indicated that the hydrophobic interactions played a major role in the process. In addition, the alterations of HSA secondary structure in the presence of phthalate plasticizers were investigated. Molecular modeling and displacement experiments showed that phthalate plasticizers situated within subdomain IIA (site I) of HSA. Furthermore, the binding distances for the plasticizers-HSA system were provided by the efficiency of fluorescence resonance energy transfer.