Synthesis, characterization and interaction studies of copper based drug with Human Serum Albumin (HSA): Spectroscopic and molecular docking investigations

A new water soluble copper(II) complex, [Cu(glygly)(ssz)(H2O)]center dot 6H(2)O, 1 derived from dipeptide (glycyl glycine anion) and sulfasalazine was synthesized and characterized by elemental analysis (CHN), molar conductance measurements and spectroscopic methods (IR. UV-vis, ESI-MS). The complex 1 is non-ionic in nature and possess octahedral geometry around Cu(II) metal ion. The interaction of complex 1 with Human Serum Albumin (HSA) was investigated under physiological condition in Tris-HCl buffer solution at pH 7.4 by means of various spectroscopic methods (fluorescence, CD and FTIR) and molecular docking technique. The results of fluorescence titration revealed that the complex 1 strongly quench the intrinsic fluorescence of HSA through a static quenching procedure. Binding constants (K-b) and the number of binding sites (n approximate to 1) were calculated using modified Stern-Volmer equations. The thermodynamic parameters Delta G at different temperatures were calculated subsequently the value of Delta H and Delta S was also calculated which revealed that the hydrophobic and hydrogen bonding interactions play a major role in HSA-complex 1 association. The distance r between donor (HSA) and acceptor (complex 1) was obtained according to fluorescence resonance energy transfer and the alterations of HSA secondary structure induced by complex 1 were confirmed by FT-IR and CD measurements. (C) 2012 Elsevier B.V. All rights reserved.