Continuous dissolution of structure during the unfolding of a small protein
Continuous dissolution of structure during the unfolding of a small protein
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DOI：
10.1073/pnas.0812564106
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发表时间：
2009-07-07
影响因子：
11.1
通讯作者：
Udgaonkar, Jayant B.
中科院分区：
文献类型：
--
作者：
Jha, Santosh Kumar;Dhar, Deepak;Udgaonkar, Jayant B.
当用荧光和圆二色谱等系综平均探针测量时，许多小蛋白的去折叠动力学似乎是一级的。对于一种这样的蛋白质，Monellin，这里表明，在这种欺骗性的简单背后隐藏着一种复杂性，这种复杂性通过使用能够区分一组结构中的不同构象的实验探测器而变得明显。在这项研究中，通过测量4个不同分子内距离分布的变化，利用多位点时间分辨荧光共振能量转移方法来探索Monellin的去折叠。在展开的过程中，可以看到蛋白质分子经历了缓慢的、持续的、扩散的膨胀。溶胀过程可以被模拟为具有一些额外的非共价分子内相互作用的Rouse-like链的缓慢扩散溶胀。在这里，我们展示了特定的结构在膨胀过程中逐渐丢失，而不是在展开过程中以一种要么全有要么全不的方式丢失。
The unfolding kinetics of many small proteins appears to be first order, when measured by ensemble-averaging probes such as fluorescence and circular dichroism. For one such protein, monellin, it is shown here that hidden behind this deceptive simplicity is a complexity that becomes evident with the use of experimental probes that are able to discriminate between different conformations in an ensemble of structures. In this study, the unfolding of monellin has been probed by measurement of the changes in the distributions of 4 different intramolecular distances, using a multisite, time-resolved fluorescence resonance energy transfer methodology. During the course of unfolding, the protein molecules are seen to undergo slow and continuous, diffusive swelling. The swelling process can be modeled as the slow diffusive swelling of a Rouse-like chain with some additional noncovalent, intramolecular interactions. Here, we show that specific structure is lost during the swelling process gradually, and not in an all-or-none manner, during unfolding.