Centre de Recherche sur la Matiére Divisée, UMR 6619-CNRS, Université d'Orléans, 1b rue de la Férollerie, 45071 Orléans Cedex 2, France.
J Phys Chem B. 2011 Mar 3;115(8):1881-8. doi: 10.1021/jp104769v. Epub 2011 Feb 3.
The present work investigates the effects of H/D isotopic substitution on the structural and thermodynamic stability of bovine serum albumin (BSA) in aqueous solution over the temperature range of 5-90 °C. Using far-ultraviolet circular dichroism, we have compared protein unfolding pathways in H(2)O and D(2)O. Our results show that BSA possesses similar conformations in H(2)O and D(2)O at temperatures below 50 °C but follows different unfolding pathways at higher temperatures. The presence of D(2)O retards the occurrence of irreversible thermal denaturation in BSA, as evidenced by a higher onset temperature of 58 °C, in contrast to 50 °C in H(2)O. D(2)O exhibits a protective effect on the domain structure during the early stages of domain denaturation. Following incubation at 90 °C over a period of minutes, D(2)O causes a rapid aggregation of BSA molecules. This behavior is not observed in H(2)O solutions. Meanwhile, H/D substitution does not influence the reversible structural transformation of the protein in a significant manner. Partly renatured BSA in H(2)O and D(2)O undergoes very similar reversible structural transformations during a second heating cycle.
本工作研究了在 5-90°C 的温度范围内，H/D 同位素取代对水溶液中牛血清白蛋白（BSA）的结构和热力学稳定性的影响。通过远紫外圆二色性，我们比较了 H 2 O 和 D 2 O 中蛋白质的展开途径。我们的结果表明，BSA 在低于 50°C 的温度下在 H 2 O 和 D 2 O 中具有相似的构象，但在较高温度下遵循不同的展开途径。D 2 O 的存在延迟了 BSA 不可逆热变性的发生，其起始温度为 58°C，而在 H 2 O 中为 50°C。D 2 O 在结构域变性的早期阶段对结构域结构表现出保护作用。孵育 90°C 数分钟后，D 2 O 会导致 BSA 分子迅速聚集。在 H 2 O 溶液中不会观察到这种行为。同时，H/D 取代不会显著影响蛋白质的可逆结构转化。在第二次加热循环中，部分复性的 BSA 在 H 2 O 和 D 2 O 中经历非常相似的可逆结构转化。
