Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina, 27599.
Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina, 27599.
Protein Sci. 2018 Sep;27(9):1710-1716. doi: 10.1002/pro.3477.
The stability of a protein is vital for its biological function, and proper folding is partially driven by intermolecular interactions between protein and water. In many studies, H O is replaced by D O because H O interferes with the protein signal. Even this small perturbation, however, affects protein stability. Studies in isotopic waters also might provide insight into the role of solvation and hydrogen bonding in protein folding. Here, we report a complete thermodynamic analysis of the reversible, two-state, thermal unfolding of the metastable, 7-kDa N-terminal src-homology 3 domain of the Drosophila signal transduction protein drk in H O and D O using one-dimensional F NMR spectroscopy. The stabilizing effect of D O compared with H O is enthalpic and has a small to insignificant effect on the temperature of maximum stability, the entropy, and the heat capacity of unfolding. We also provide a concise summary of the literature about the effects of D O on protein stability and integrate our results into this body of data.
蛋白质的稳定性对其生物功能至关重要，而蛋白质的正确折叠部分是由蛋白质和水之间的分子间相互作用驱动的。在许多研究中，H₂O 被 D₂O 取代，因为 H₂O 会干扰蛋白质信号。然而，即使是这种微小的干扰也会影响蛋白质的稳定性。在同位素水中的研究也可能提供对溶剂化和氢键在蛋白质折叠中的作用的深入了解。在这里，我们使用一维 ¹⁵N NMR 光谱法报告了在 H₂O 和 D₂O 中，使用可逆的、两态的、热展开的、不稳定的 7kDa 果蝇信号转导蛋白 drk 的 N 端Src 同源结构域 3 域的完整热力学分析。与 H₂O 相比，D₂O 的稳定作用是焓的，并且对最大稳定性温度、熵和展开的热容的影响很小或没有影响。我们还对关于 D₂O 对蛋白质稳定性影响的文献进行了简洁的总结，并将我们的结果纳入了这一数据体。
