SO2-Induced Solution Phase Transition of Water-Soluble and α-Helical Polypeptides

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• 作者：Mengxiang Zhu ; Yan Wu ; Chenglong Ge ; Ying Ling ; Haoyu Tang
• 刊名：Macromolecules
• 出版年：2016
• 出版时间：May 10, 2016
• 年：2016
• 卷：49
• 期：9
• 页码：3542-3549
• 全文大小：531K
• 年卷期：0
• ISSN：1520-5835

文摘

Water-soluble random copolypeptides bearing pyridinium tetrafluoroborate (PyBF₄) and oligo-ethylene glycol (OEG) pendants (PPLG-PyBF₄-r-OEG) showed SO₂-induced solution phase transition. They were prepared by sequential postpolymerizations including nucleophilic substitution of poly(γ-3-chloropropyl-l-glutamate) with sodium azide to partially convert chloro groups into azido groups, copper-mediated [2 + 3] alkyne–azide 1,3-dipolar cycloaddition to conjugate OEG pendants, another nucleophilic substitution to conjugate pyridinium chloride, and ion-exchange reaction. FTIR and CD analysis revealed that PPLG-PyBF₄-r-OEG samples with suitable molar content of PyBF₄ (x ≤ 0.4) were water-soluble and adopted α-helical conformation in both the solid-state and aqueous solution. UV–vis spectroscopy and dynamic light scattering (DLS) results revealed that PPLG-PyBF₄-r-OEG aqueous solution underwent a reversible solution phase transition by sequentially bubbling SO₂ and N₂. ¹H NMR analysis suggested that SO₂ interacted with triazole groups and induced the solution phase transition.