Binding affinity studies of 1, 2, 3-triazole copper(II) complexes to human serum albumin. Issue 11 (3rd July 2018)

• Record Type: Journal Article
• Authors: de Paula, Queite A.; Joly, Jean-Pierre; Selmeczi, Katalin; Fonseca, David E. P.; Caramori, Giovanni F.; Farrell, Nicholas P.; Da Costa Ferreira, Ana M.
• Is Part Of: Journal of coordination chemistry. Volume 71:Issue 11/13(2018)
• Page Start: 1894
• Page End: 1909
• Publication Date: 2018-07-03
• Subjects: 1, 2, 3-Triazole-copper(II) complexes -- HSA binding -- CD spectroscopy -- fluorescence measurements -- DFT calculations; Coordination compounds -- Periodicals; 541.2242
• DOI: 10.1080/00958972.2018.1495331
• Languages: English
• ISSNs: 0095-8972

Abstract

Abstract: Two copper(II) complexes with tetradentate 1, 4-disubstituted-1, 2, 3-triazole ligands, [CuL (MeCN)](ClO4 )2 (1 ) and [CuL ′](ClO4 )2 (2 ), have been prepared and characterized by different techniques, including X-ray structure determination, spectroscopic, and electrochemical measurements, as reported elsewhere. Herein, we report the interactions of these complexes, and corresponding free ligands, with human serum albumin (HSA) verifying their relative thermodynamic stability and differences in binding to this protein. Interactions with HSA were verified by CD measurements monitored at 564 nm, up to stoichiometric ratio 2:1 [Complex]:[protein], according to competitive equilibria involving the insertion of copper at the selective N -terminal metal binding site in HSA, and additionally at a secondary nonselective site. Further interactions of these complexes with L -tryptophan residues, and probable supplementary site(s) for the binding, were followed by fluorescence measurements. Analogous experiments with the freeL andL ′ indicated much weaker interactions. Protein oxidation damage was observed for both complexes, monitored by carbonyl groups formation in the presence of H2 O2, probably with the participation of reactive oxygen species. Density functional theory calculations exhibit metal-ligand binding interaction energies similar to [Cu(HSA-Nterminal )] +, and reinforced the experimental results, showing clearly that such triazole ligands are competitive toward copper(II) in biological medium. GRAPHICAL ABSTRACT: