Probing the interactions of novel europium coordination complexes with serum albumin

Molecular interactions between novel europium coordination complexes (EC) possessing superior cytotoxic activity and bovine serum albumin (BSA), the most prominent representative of plasma proteins, were assessed using fluorescence spectroscopy and molecular docking techniques. Cumulative results from fluorescent probe binding, fluorescence quenching and Förster resonance energy transfer studies revealed that the europium complexes V4 and V8 do not perturb the BSA structure, while V3, V5, and V7 induce partial unfolding of the polypeptide chain. Molecular docking studies coupled with analysis of the three-dimensional structure of the BSA-EC complexes showed that V4 and V8 reside in the vicinity of the protein IIA subdomain (Sudlow's site I), while V3, V5 and V5 were localized predominantly in the BSA IIIA subdomain (Sudlow's site II). Due to the intactness of the protein structure upon association with V4 and V8, these compounds may be recommended for further evaluation as potential antineoplastic agents.