title: Effect of pyrrolidinium based ionic liquid on the channel form of gramicidin in lipid vesicles.
abstract: The present work is focused on the interaction between membrane bound gramicidin and 1-butyl-1-methyl-2-oxopyrrolidinium bromide (BMOP) ionic liquid. Ionic liquids (ILs) are solvents that are often liquid at room temperature and composed of organic cation and appropriate anion. The gramicidin peptide forms prototypical ion channels for cations, which have been extensively used to study the organization, dynamics, and function of membrane spanning channels. The interaction was studied by circular dichroism, steady state, time-resolved fluorescence spectroscopy in combination with dynamic surface tension and field emission scanning electron microscopic methods (FESEM). The results obtained from circular dichroism shows that the BMOP interacts with the channel form of gramicidin in lipid vesicle without any considerable effect on its conformation. The Red-edge excitation shift (REES) also supported the above findings. In addition, the fluorescence studies suggested that BMOP makes ground state complex with ion channel, which was further supported by time resolved measurements. Furthermore, dynamic surface tension analysis shows the faster adsorption of BMOP with membrane bound gramicidin at the air-water interface. Additionally, FESEM results indicated that BMOP forms a film around the membrane bound gramicidin at higher concentration. These results are potentially useful to analyze the effect of ionic liquids on the behaviour of membrane proteins.
authors.affiliation: Biophysical Chemistry Laboratory, Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia (A Central University), New Delhi 110025, India.
authors.forename: Upendra Kumar
authors.initials: UK
authors.lastname: Singh
authors.affiliation: Biophysical Chemistry Laboratory, Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia (A Central University), New Delhi 110025, India.
authors.forename: Neeraj
authors.initials: N
authors.lastname: Dohare
authors.affiliation: Biophysical Chemistry Laboratory, Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia (A Central University), New Delhi 110025, India.
authors.forename: Prabhash
authors.initials: P
authors.lastname: Mishra
authors.affiliation: Department of Chemistry, A.R.S.D. College, University of Delhi, Delhi 110021, India.
authors.forename: Prashant
authors.initials: P
authors.lastname: Singh
authors.affiliation: Polymer and Biophysics Laboratory, School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
authors.forename: Himadri B
authors.initials: HB
authors.lastname: Bohidar
authors.affiliation: Biophysical Chemistry Laboratory, Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia (A Central University), New Delhi 110025, India. Electronic address: rpatel@jmi.ac.in.
authors.forename: Rajan
authors.initials: R
authors.lastname: Patel
mesh_terms: D002462:Cell Membrane / Q000737:chemistry; D006096:Gramicidin / Q000737:chemistry*; D052578:Ionic Liquids / Q000494:pharmacology*; D011487:Protein Conformation / Q000187:drug effects; D011759:Pyrrolidines / Q000494:pharmacology*; D011760:Pyrrolidinones / Q000494:pharmacology*; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology*; D013500:Surface Tension; D013696:Temperature; D053835:Unilamellar Liposomes / Q000737:chemistry*
chemical_list: C000606700:1-butyl-1-methyl-2-oxopyrrolidinium; D052578:Ionic Liquids; D011759:Pyrrolidines; D011760:Pyrrolidinones; D000644:Quaternary Ammonium Compounds; D053835:Unilamellar Liposomes; D006096:Gramicidin
keywords: Dynamic surface tension; Gramicidin; Ionic liquid; Lipid vesicles; Red-edge excitation