Title
Comparative study of an osazone based ligand and its palladium(II) complex with human serum albumin: A spectroscopic, thermodynamic and molecular docking approach
Author
Nirmalya Bandyopadhyay, Ankur Bikash Pradhan, Suman Das, Jnan Prakash Naskar
Year
2017
Journal
Journal of Photochemistry and Photobiology B: Biology
Abstract
An osazone based ligand, hexane-3,4-dione-bis(2′-phenylhydrazone) (LH2), was synthesized by 1:2 M Schiff base condensation of 3,4-hexanedione and phenylhydrazine in dehydrated methanol. Its palladium(II) complex (1) has also been synthesized. LH2and 1 have thoroughly been characterized by several spectroscopic and analytical means. DFT optimized structure of 1 shows that it is a monomeric Pd(II) complex having ‘N2Cl2’ coordination chromophore. Our BVS analysis also satisfactorily reproduces the oxidation number of the palladium center. 1 shows irreversible Pd(II)/Pd(I) reduction in its CV in methanol. 1 is three-fold more emissive than LH2. This enhanced emission has also been supported by time correlated single photon counting (TCSPC) measurements at room temperature. Human serum albumin (HSA) binding aspects of both LH2 and 1 have been investigated through various biophysical techniques. The binding constants as determined from Benesi-Hilderbrand plot using the absorbance spectral analyses were found respectively to be 1.18 × 105 and 4.38 × 104 M− 1 for LH2 and 1. The experimental findings confirm that both are good HSA binders. The thermodynamic parameters (∆ G°, ∆ H° and ∆ S°) have also been evaluated by isothermal titration calorimetric (ITC) experiments. These parameters indicate that the binding processes are spontaneous both for LH2 and 1. Molecular docking analyses reveal that both LH2and 1 reside in domain-I of HSA.
Instrument
J-815
Keywords
Circular dichroism, Secondary structure, Ligand binding, Protein folding, Biochemistry