Interaction between holo transferrin and HSA–PPIX complex in the presence of lomefloxacin: An evaluation of PPIX aggregation in protein–protein interactions

Abstract

Human serum albumin (HSA) and holo transferrin (TF) are two serum carrier proteins that are able to<br><br>interact with each other, thereby altering their binding behavior toward their ligands. During the course<br><br>of this study, the interaction between HSA–PPIX and TF, in the presence and absence of lomefloxacin<br><br>(LMF), was for the first time investigated using different spectroscopic and molecular modeling techniques.<br><br>Fluorescence spectroscopy experiments were performed in order to study conformational<br><br>changes of proteins. The RLS technique was utilized to investigate the effect of LMF on J-aggregation of<br><br>PPIX, which is the first report of its kind. Our findings present clear-cut evidence for the alteration of<br><br>interactions between HSA and TF in the presence of PPIX and changes in drug-binding to HSA and<br><br>HSA–PPIX complex upon interaction with TF. Moreover, molecular modeling studies suggested that the<br><br>binding site for LMF became switched in the presence of PPIX, and that LMF bound to the site IIA of<br><br>HSA. The obtained results should give new insight into research in this field and may cast some light<br><br>on the dynamics of drugs in biological systems.