Spectroscopic and docking studies on the interaction between pyrrolidinium based ionic liquid and bovine serum albumin

The interaction of synthesized ionic liquid, 1-butyl-1-methyl-2-oxopyrrolidinium bromide (BMOP) and bovine serum albumin (BSA) was investigated using UV-Vis, FT-IR, steady state and time resolved fluorescence measurements and docking studies. Steady state spectra revealed that BMOP strongly quenched the intrinsic fluorescence of BSA through dynamic quenching mechanism. The corresponding thermodynamic parameters; Gibbs free energy change (AG), entropy change (Delta S) and enthalpy change (Delta H) showed that the binding process was spontaneous and entropy driven. It is also indicated that hydrophobic forces play a key role in the binding of BMOP to BSA. The synchronous fluorescence spectroscopy reveals that the conformation of BSA changed in the presence of BMOP. The shift in amide I band of FT-IR spectrum of BSA suggested unfolding of the protein secondary structure upon the addition of BMOP. In addition, the molecular modeling study of BSA-BMOP system shows that BMOP binds with BSA at the interface between two sub domains IIA and IIIA, which is located just above the entrance of the binding pocket of IIA through hydrophobic and hydrogen bond interactions in which hydrophobic interaction are dominated. (C) 2014 Elsevier B.V. All rights reserved.