Do protein molecules unfold in a simple shear flow?
Do protein molecules unfold in a simple shear flow?
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DOI：
10.1529/biophysj.106.089367
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发表时间：
2006-11-01
影响因子：
3.4
通讯作者：
Hagen, Stephen J.
中科院分区：
文献类型：
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作者：
Jaspe, Juan;Hagen, Stephen J.
蛋白质分子通常在经受极端的热、冷、pH、溶剂组成或机械应力时展开（变性）。人们可能会认为，由不均匀的流体流动引起的剪切力也会使蛋白质不稳定，就像蛋白质溶液快速流过狭窄的通道一样。然而，尽管蛋白质文献中包含许多关于剪切变性的参考文献，但我们几乎没有发现这种现象的定量证据。我们已经研究了高剪切力是否可以使小球状蛋白不稳定到任何可测量的程度。我们研究了一种蛋白质（马细胞色素c，104个氨基酸），其荧光在展开时急剧增加。通过迫使样品以接近10 m/s的速度通过石英毛细管（内径150-180 μ m），我们使蛋白质经受高达2 × 10（5）s（-1）的剪切速率dv（z）/dr，同时用紫外激光照射它。我们可以很容易地检测到<1%的荧光变化，对应于
Protein molecules typically unfold (denature) when subjected to extremes of heat, cold, pH, solvent composition, or mechanical stress. One might expect that shearing forces induced by a nonuniform fluid flow would also destabilize proteins, as when a protein solution flows rapidly through a narrow channel. However, although the protein literature contains many references to shear denaturation, we find little quantitative evidence for the phenomenon. We have investigated whether a high shear can destabilize a small globular protein to any measurable extent. We study a protein (horse cytochrome c, 104 amino acids) whose fluorescence increases sharply upon unfolding. By forcing the sample through a silica capillary (inner diameter 150-180 mu m) at speeds approaching 10 m/s, we subject the protein to shear rates dv(z)/dr as large as similar to 2 x 10(5) s(-1) while illuminating it with an ultraviolet laser. We can readily detect fluorescence changes of < 1%, corresponding to shifts of