Hairpin folding dynamics: The cold-denatured state is predisposed for rapid refolding
Hairpin folding dynamics: The cold-denatured state is predisposed for rapid refolding
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DOI：
10.1021/bi050698z
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发表时间：
2005-08-02
期刊：
影响因子：
2.9
通讯作者：
Andersen, NH
中科院分区：
文献类型：
--
作者：
Dyer, RB;Maness, SJ;Andersen, NH
冷变性是球状蛋白的普遍现象，相关的蛋白质冷变性状态具有重要的基础和实际意义。在这里，我们表征了 8% 六氟-2-丙醇 (HFIP) 中 β-发夹形成肽 MrH3a 的冷变性状态及其在激光诱导 T 跳跃后重折叠的动力学。 β-发夹构成了一类重要的蛋白质结构元件，但其折叠机制尚不完全清楚。使用 NMR、CD 和 IR 光谱对 MrH3a 进行表征，揭示了冷变性状态下的残余结构，与高度无序的热变性状态形成鲜明对比。冷变性状态下的残余结构包含相对致密且受溶剂保护的构象。此外，我们发现与热变性状态相比，冷变性状态的折叠速率显着加快。此外，20% HFIP 中不存在冷变性状态；折叠仅在完全展开状态下发生，并且速度明显较慢。我们将 8% HFIP 中 MrH3a 折叠速率的加速解释为冷变性状态折叠构象的直接结果。最后，当从冷变性状态开始时，循环搜索成本可能会有所减少，因为该状态可能已经形成了一些稳定的跨链相互作用。
Cold denaturation is a general phenomenon in globular proteins, and the associated cold-denatured states of proteins have important fundamental and practical significance. Here, we have characterized the cold-denatured state of a beta-hairpin forming peptide, MrH3a, in 8% hexafluoro-2-propanol (HFIP) and the dynamics of its refolding following a laser-induced T-jump. beta-Hairpins constitute an important class of protein structural elements, yet their folding mechanisms are not fully understood. Characterization of MrH3a using NMR, CD, and IR spectroscopies reveals residual structure in the cold-denatured state, in contrast with the highly disordered heat-denatured state. The residual structure in the cold-denatured state comprises relatively compact and solvent protected conformations. Furthermore, we find a substantial acceleration in the rate of folding from the cold-denatured state compared to that of the heat-denatured state. In addition, the cold-denatured state is not populated in 20% HFIP; folding occurs only from the fully unfolded state and is significantly slower. We interpret the acceleration of the folding rate of MrH3a in 8% HFIP as a direct consequence of the collapsed conformations of the cold-denatured state. Finally, there may be some reduction of the loop search cost when starting from the cold-denatured state, since this state may have some of the stabilizing cross-strand interactions already formed.