Differential binding modes of anti-cancer, anti-HIV drugs belonging to isatin family with a model transport protein: A joint refinement from spectroscopic and molecular modeling approaches

作者：Ray Debarati; Paul Bijan K; Guchhait Nikhil^*

来源：Journal of Photochemistry and Photobiology B: Biology , 2013, 127: 18-27.

DOI：10.1016/j.jphotobiol.2013.06.016

• Drug isatin and methyl isatin
• Protein BSA
• Drug protein interaction
• Fluorescence
• CD
• AutoDock simulation

The present contribution reports a detailed characterization of the binding interaction of two potential anticancer, anti-HIV drugs isatin (IST) and 1-methylisatin (MI) with model transport protein Bovine Serum Albumin (BSA). Thermodynamic parameters e.g., Delta H, Delta S and Delta G for the binding phenomenon have been evaluated on the basis of van%26apos;t Hoff equation to understand the force behind the binding process. A combined application of steady-state and time-resolved fluorescence spectroscopic techniques substantiate the observed drug-induced quenching of intrinsic tryptophanyl fluorescence of the protein to proceed through a static mechanism. Circular dichroic (CD), synchronous fluorescence and excitation-emission matrix fluorescence spectroscopic techniques have been exploited to delineate the secondary and tertiary conformational changes in the protein structure induced by the binding of drugs (IST/MI). The probable binding location of the drug molecules within the protein cavity (hydrophobic subdomain IIIA) has been explored from AutoDock-based blind docking simulation. Examination of drug-protein binding kinetics using stopped-flow fluorescence technique reveals that the association constants (k(a)) for IST-BSA and MI-BSA interactions are 1.09 x 10(-3) s(-1) (+/- 5%) and 1.73 x 10(-3) s(-1) (+/- 5%), respectively, at the experimental temperature (T) of 298 K. The present study also delves into the effect of drug-binding on the esterase activity of the protein which is found to be reduced in the drug-protein conjugate system in comparison with the native protein.

• 出版日期2013-10-5