Study on interaction of N,N′-(2-hydroxy-3-methoxybenzyl) diamine cerium(IV) with bovine serum albumin

Abstract

Complexes of cerium(IV) with bis(N,N′-(2-hydroxy-3-methoxybenzyl) ethane-1,2-diamine, bis(2-hydroxy-3-methoxybenzyl) propane-1,2-diamine and bis(2-hydroxy-3-methoxybenzyl) propane-1,3-diamine were synthesized by reaction of cerium(IV) nitrate and the ligands. The obtained coordination compounds have also been characterized by elemental analysis, IR spectroscopy, and single crystal X-ray diffraction. The interactions of these complexes with bovine serum albumin (BSA) were investigated using fluorescence spectroscopy under the simulated physiological conditions. Fluorescence titration revealed that the complexes can quench the intrinsic fluorescence of BSA through static quenching mechanism. The static quenching constants, the binding constants, and the binding sites were also acquired according to the Stern–Volmer equation and the corresponding thermodynamic parameters ΔH, ΔS, and ΔG were calculated through the van’t Hoff equation. Hydrogen bonds and van der Waals forces were the predominant intermolecular forces between these complexes and BSA. The distances between BSA and these complexes were less than 8 nm, indicating that energy transfer between the donor and acceptor occurs with high probability. Synchronous fluorescence studies indicate that binding of these complexes with BSA changes the polarity around tyrosine residues rather than tryptophan residues.