Biamphiphilic Ionic Liquid Induced Folding Alterations in the Structure of Bovine Serum Albumin in Aqueous Medium

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• 作者：Pankaj Bharmoria ; K. Srinivasa Rao ; Tushar J. Trivedi ; Arvind Kumar
• 刊名：Journal of Physical Chemistry B
• 出版年：2014
• 出版时间：January 9, 2014
• 年：2014
• 卷：118
• 期：1
• 页码：115-124
• 全文大小：570K
• ISSN：1520-5207

文摘

3-Methyl-1-octylimidazolium dodecylsulfate, [C₈mim][C₁₂OSO₃], a vesicle forming biamphiphilic ionic liquid (BAIL) (J. Phys. Chem. B 2012, 116, 14363鈥?4374), has been found to induce significant folding alterations in the structure of bovine serum albumin (BSA) in the aqueous medium at pH 7.0. Such alterations have been investigated in detail using various physicochemical and spectroscopic techniques. Different concentration regimes (monomeric, shared aggregation, and post-vesicular) of [C₈mim][C₁₂OSO₃]鈥揃SA interactions have been defined through adsorption and binding isotherms using tensiometry and isothermal titration calorimetry (ITC). Fluorimetry, circular dichroism (CD), and dynamic light scattering (DLS) measurements have shown that [C₈mim][C₁₂OSO₃] induces a small unfolding of BSA in the monomeric regime at low concentration (designated as C_f), which is followed by a refolding up to critical aggregation concentration (CAC) (designated as C₁). Above C₁, i.e., in the shared aggregation concentration regime, again a small unfolding of BSA was observed up to critical vesicular concentration (CVC) (designated as C₂). In the vesicular and post-vesicular regimes, the BSA remained stable against folding alterations. The kinetic stability of BSA in the vesicular concentration regimes was studied for a month using turbidimetry. It has been found that [C₈mim][C₁₂OSO₃] stabilizes BSA against the aggregation which is the major cause of protein destabilization. The present study gives insights for the design of surface active ILs for protein stabilization as a potential replacement for the mixed micelles of conventional surfactants used in detergent industries for enzyme stabilization and as an artificial chaperone.