title: The Overriding Roles of Concentration and Hydrophobic Effect on Structure and Stability of Heme Protein Induced by Imidazolium-Based Ionic Liquids.
abstract: Spectroscopic and molecular docking investigations were carried out to characterize the effect of imidazolium-based ionic liquids (ILs) with varying chain length of the cation on the thermal stability as well as spectroscopic behavior of heme protein hemoglobin (Hb). The goal of this work is to investigate the role of concentration of ILs, the effect of alkyl chain length of the cation, and the related Hofmeister series on the structure of Hb. To achieve this goal, a series of ILs possessing same Cl(-) anion and a set of cation [Cnmim](+) with increasing chain length such as 1-ethyl-3-methylimidazolium chloride ([Emim][Cl]), 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]), 1-hexyl-3-methylimidazolium chloride ([Hmim][Cl]), and 1-decyl-3-methylimidazolium chloride ([Dmim][Cl]) were used in this study. It was observed that the stability of the protein was concentration dependent as well as the hydrophobic interactions between [Cnmim](+) of ILs, and the amino acid residues in the protein played a major role in protein unfolding. As a consequence, the destabilization tendency of the ILs toward the Hb increases with increasing chain length of the cation of ILs. Additionally, the cations of the ILs obeyed the Hofmeister series when arranged in the order of providing stability to Hb structure.
authors.affiliation: Department of Chemistry, University of Delhi, Delhi 110 007, India.
authors.forename: Indrani
authors.initials: I
authors.lastname: Jha
authors.affiliation: Department of Chemistry, University of Delhi, Delhi 110 007, India.
authors.forename: Awanish
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Department of Chemistry, University of Delhi, Delhi 110 007, India.
authors.forename: Pannuru
authors.initials: P
authors.lastname: Venkatesu
mesh_terms: D000817:Anilino Naphthalenesulfonates / Q000737:chemistry; D001881:Borates / Q000737:chemistry; D002942:Circular Dichroism; D005453:Fluorescence; D006420:Hemeproteins / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D007093:Imidazoles / Q000737:chemistry; D052578:Ionic Liquids / Q000737:chemistry*; D062105:Molecular Docking Simulation; D055550:Protein Stability; D017433:Protein Structure, Secondary; D014364:Tryptophan / Q000737:chemistry
chemical_list: C528767:1-hexyl-3-methylimidazolium; C515594:8-anilino-1-naphthalenesulfonic acid; D000817:Anilino Naphthalenesulfonates; D001881:Borates; D006420:Hemeproteins; D007093:Imidazoles; D052578:Ionic Liquids; C502841:1-butyl-3-methylimidazolium chloride; D014364:Tryptophan; C518739:1-ethyl-3-methylimidazolium