Unravelling the distinctive mode of cooperative and independent interaction mechanism of 1-butyl-2,3-dimethylimidazolium tetrafluoroborate ionic liquid with model transport proteins by comprehensive spectroscopic and computational studies

Abstract

In the present investigation, a detailed spectroscopic analysis on the interaction mechanism of 1-Butyl-2,3-dimethylimidazolium tetrafluoroborate [Bdmim][BF4] with human serum albumin (HSA) and bovine serum albumin (BSA) has been carried out by multispectroscopic studies. The results obtained from the fluorescence titration experiments indicated the existence of a weak interaction between HSA/BSA and [Bdmim][BF4]. The binding parameters revealed that [Bdmim][BF4] binds to HSA by cooperative process, while in the case of BSA the binding of [Bdmim][BF4] is found to be independent to the binding sites having the similar affinity. The outcome of the CD and absorbance spectral experiments of HSA/BSA-[Bdmim][BF4] systems revealed the occurrence of very little modifications in the micro-environmental and secondary structural conformations of HSA/BSA. Autodocking and molecular dynamics simulation studies indicated that the positively charged imidazolium moieties of ionic liquid (IL) is located in the vicinity of subdomain IIA and subdomain IB in HSA and BSA, respectively. The enzyme-like activity of HSA/BSA is inhibited slightly upon complexation with [Bdmim][BF4].