Complex Ion Effects on Polypeptide Conformational Stability: Chloride and Sulfate Salts of Guanidinium and Tetrapropylammonium
Complex Ion Effects on Polypeptide Conformational Stability: Chloride and Sulfate Salts of Guanidinium and Tetrapropylammonium
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DOI：
10.1021/ja201349g
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发表时间：
2011-05-18
影响因子：
15
通讯作者：
Jungwirth, Pavel
中科院分区：
文献类型：
--
作者：
Dempsey, Christopher E.;Mason, Philip E.;Jungwirth, Pavel
用圆二色谱研究了氯化物和硫酸盐四丙基铵(TPA(+))和胍(GDM(+))对色氨酸拉链(Trpzip)和α-螺旋多肽(Alahel)构象稳定性的影响。与GDM(+)一样，TPA(+)与平面色氨酸吲哚基团相互作用，干扰TrpZip多肽的构象稳定性。TPA(+)效应基本上不受硫酸盐的影响，这表明在浓硫酸溶液中没有观察到的杂离子配对。TPA(+)稳定Alahel多肽中的螺旋构象，表明从多肽键中排除。这些观察结果与分子动力学模拟的预测大体一致[Mason，P.E.；et al.J.Phys.化学。B2009,113,3227-3234]，表明络合离子对蛋白质的影响在离子水化、与特定蛋白质基团的互补相互作用和离子配对贡献方面越来越可预测。
The effects of chloride and sulfate salts of tetrapropylammonium (TPA(+)) and guanidinium (Gdm(+)) on the conformational stabilities of tryptophan zipper (trpzip) and alpha-helical (alahel) peptides were measured by circular dichroism spectroscopy. Like Gdm(+), TPA(+) interacts with the planar tryptophan indole group, perturbing the conformational stability of trpzip peptides. TPA(+) effects are largely unaffected by sulfate, indicating an absence of the heteroion pairing that is observed in concentrated Gdm(2)SO(4) solutions. TPA(+) stabilizes helical conformations in alahel peptides, indicating exclusion from the peptide bond. The observations are broadly consistent with predictions of molecular dynamics simulations [Mason, P. E.; et al. J. Phys. Chem. B 2009, 113, 3227-3234], indicating that the effects of complex ions on proteins are increasingly predictable in terms of ion hydration, complementary interactions with specific protein groups, and ion-pairing contributions.