Molecular Mechanisms of Ion-Specific Effects on Proteins

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• 作者：Kelvin B. Rembert ; Jana Paterov谩 ; Jan Heyda ; Christian Hilty ; Pavel Jungwirth ; Paul S. Cremer
• 刊名：The Journal of the American Chemical Society
• 出版年：2012
• 出版时间：June 20, 2012
• 年：2012
• 卷：134
• 期：24
• 页码：10039-10046
• 全文大小：481K
• 年卷期：v.134,no.24(June 20, 2012)
• ISSN：1520-5126

文摘

The specific binding sites of Hofmeister ions with an uncharged 600-residue elastin-like polypeptide, (VPGVG)₁₂₀, were elucidated using a combination of NMR and thermodynamic measurements along with molecular dynamics simulations. It was found that the large soft anions such as SCN^{鈥?/sup> and I鈥?/sup> interact with the polypeptide backbone via a hybrid binding site that consists of the amide nitrogen and the adjacent 伪-carbon. The hydrocarbon groups at these sites bear a slight positive charge, which enhances anion binding without disrupting specific hydrogen bonds to water molecules. The hydrophobic side chains do not contribute significantly to anion binding or the corresponding salting-in behavior of the biopolymer. Cl鈥?/sup> binds far more weakly to the amide nitrogen/伪-carbon binding site, while SO₄2鈥?/sup> is repelled from both the backbone and hydrophobic side chains of the polypeptide. The Na+ counterions are also repelled from the polypeptide. The identification of these molecular-level binding sites provides new insights into the mechanism of peptide鈥揳nion interactions.}