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Peculiar reactivity of a di-imine copper(ii) complex regarding its binding to albumin protein†
Vivian C.Silveira,a Mariamãng cầu P.Abbott,a MaurícioCavicchioli,a Marcos B.Gonçalves,b Helemãng cầu M.Petrilli,b Leandrode Rezende,a Antonia T.Amaral,a David E. Phường.Fonseca,c Giovanni F.Caramoric& Ana M.da Costa Ferreira*a
* Corresponding authors
a Instituto lớn de Química, Universidade de São Paulo, São Paulo, SP.., Brazil E-mail: amdcferr
b Instituto lớn de Física, Universidade de São Paulo, São Paulo, SP., Brazil
c Departamenkhổng lồ de Química, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
A phối of four di-imine copper(II) complexes containing pyridine, pyrazine and/or imidazole moieties, apyhist)H2O>2+1 (apyhist = 2-(1H-imidazol-4-yl)-N-(1-(pyridin-2-yl)ethylidene)ethanamine), apzhist)OH>+2 (apzhist = 2-(1H-imidazol-4-yl)-N-(1-(pyrazin-2-yl)ethylidene)ethanamine), apyepy)OH>+3 (apyepy = 2-(pyridin-2-yl)-N-(1-(pyridin-2-yl)ethylidene)ethanamine), và apzepy)H2O>2+4 (apzepy = N-(1-(pyrazin-2-yl)ethylidene)-2-(pyridin-2-yl)ethanamine), were investigated regarding their capability of interacting with serum albumin (human, HSA and bovine, BSA), by using spectroscopic techniques, CD, UV/Vis và Equảng bá. Like other similar di-imine copper(II) complexes, most of them showed an expected preferential insertion of the metal ion at the primary N-terminal site of the protein, very selective sầu for copper và characterized by a CD bvà at 560 nm. Further insertion of the copper ion at a secondary site is expected when using an excess of the metal. However, one of these studied complexes, apyhist)H2O>2+1, exhibited anomalous behaviour interacting only at this secondary metal binding site of albumin, characterized by a CD bvà at 370 nm, và attributed khổng lồ the coordination of copper at the Cys34 pocket. Analogous experiments with HSA previously treated with N-ethyl-maleimide (NEM), that oxidizes the protein Cys34 residue và obstructs the metal coordination, verified these results. Additional data obtained by Etruyền bá spectroscopy complemented those results. DFT calculations, considering some structural & electronic characteristics of such series of di-imine ligands and of the corresponding copper complexes, suggested molecular recognition of the apyhist ligvà at the protein cavity as a feasible explanation for this unexpected & peculiar behaviour of complex 1.
