Interaction of Bovine Serum Albumin with Ester-Functionalized Anionic Surface-Active Ionic Liquids in Aqueous Solution: A Detailed Physicochemical and Conformational Study

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• 作者：Xiaoqing Wang ; Jie Liu ; Limei Sun ; Li Yu ; Jingjing Jiao ; Rui Wang
• 刊名：The Journal of Physical Chemistry B
• 出版年：2012
• 出版时间：October 18, 2012
• 年：2012
• 卷：116
• 期：41
• 页码：12479-12488
• 全文大小：449K
• 年卷期：v.116,no.41(October 18, 2012)
• ISSN：1520-5207

文摘

Ester-functionalized anionic surface-active ionic liquids (SAILs), 3-methyl-1-(ethoxycarbonylmethyl)imidazolium dodecylsulfate ([C₁COOC₂C₁im][C₁₂SO₄]) and 3-methyl-1-(ethoxycarbonylmethyl)pyrrolidinium dodecylsulfate ([C₁COOC₂C₁Py][C₁₂SO₄]), were synthesized. The tensiometric profiles demonstrate that, in pure water, the studied SAILs exhibit higher surface activity than the traditional anionic surfactant, sodium dodecyl sulfate (SDS), and cationic SAILs, 1-dodecyl-3-methylimidazolium bromide ([C₁₂mim]Br) and N-dodecyl-N-methylpyrrolidimium bromide (C₁₂MPB), with the same hydrocarbon chain length. The interaction between bovine serum albumin (BSA) and the anionic SAILs in pH 7.4 buffer solution was systematically investigated by various techniques. The results show that the cationic ring has a slight effect on the BSA鈥揝AIL interaction. The binding isotherms of BSA with the SAILs display four characteristic regions with increasing SAIL concentration. The unfolding of BSA occurs in the third region. Fluorescence spectroscopy indicates that the studied SAILs cause the exposure of tryptophan residues to a hydrophobic environment, and [C₁COOC₂C₁im][C₁₂SO₄] can more effectively reduce the fluorescence intensity of BSA at low SAIL concentrations than [C₁COOC₂C₁Py][C₁₂SO₄]. Circular dichroism spectroscopy evidences that the denaturation extent of BSA induced by [C₁COOC₂C₁im][C₁₂SO₄] is higher than that of [C₁COOC₂C₁Py][C₁₂SO₄].