Hyper-thermal stability and unprecedented re-folding of solvent-free liquid myoglobin
Hyper-thermal stability and unprecedented re-folding of solvent-free liquid myoglobin
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DOI：
10.1039/c2sc20143g
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发表时间：
2012-01-01
期刊：
影响因子：
8.4
通讯作者：
Mann, Stephen
中科院分区：
文献类型：
--
作者：
Brogan, Alex P. S.;Siligardi, Giuliano;Mann, Stephen
通过研究无溶剂液相中的蛋白质来分离溶剂效应以前是不可能的，因为冷冻干燥的蛋白质固体不熔化而是热降解。在这里，我们规避这个问题，通过修改肌红蛋白分子之间的相互作用，通过聚合物-表面活性剂冠层，以产生无溶剂的液相，在很宽的温度范围内热稳定。使用高分辨率的同步辐射圆二色性和紫外-可见光谱，我们确定的温度依赖性的结构和重折叠行为的阳离子化肌红蛋白在无溶剂条件下，并表明，脱水和随后的熔化的纳米结构在室温下的蛋白质二级结构没有显着的影响。值得注意的是，无溶剂的液体肌红蛋白分子表现出超嗜热行为，并且可以通过从155摄氏度冷却而可逆地重新折叠。我们属性异常高的热稳定性和持久性的蛋白质折叠熵的贡献与大分子拥挤和限制，并提出，在没有溶剂壳的情况下的重折叠是由聚合物表面活性剂冠层的构型灵活性和分子的相互作用促进。
Isolating solvent effects by studying proteins in a liquid phase devoid of solvent has not been previously possible because freeze-dried protein solids do not melt but thermally degrade. Herein we circumvent this problem by modifying the interactions between myoglobin molecules via a polymer-surfactant coronal layer to produce a solvent-free liquid phase that is thermally stable over a wide temperature range. Using high-resolution synchrotron radiation circular dichroism and UV-Vis spectroscopies we determine the temperature-dependent structure and re-folding behaviour of cationized myoglobin under solvent-free conditions, and show that dehydration and subsequent melting of the nanoconstruct has no significant effect on the protein secondary structure at room temperature. Significantly, the solvent-free liquid myoglobin molecules exhibit hyper-thermophilic behaviour and can be reversibly re-folded by cooling from 155 degrees C. We attribute the abnormally high thermal stability and persistence of protein folding to entropic contributions associated with macromolecular crowding and confinement, and propose that re-folding in the absence of a solvent shell is facilitated by the configurational flexibility and molecular interactivity of the polymer surfactant coronal layer.