Coulomb forces control the density of the collapsed unfolded state of barstar
Coulomb forces control the density of the collapsed unfolded state of barstar
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DOI：
10.1016/j.jmb.2007.11.083
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发表时间：
2008-02-15
影响因子：
5.6
通讯作者：
Ulbrich-Hofmann, Renate
中科院分区：
文献类型：
--
作者：
Hofmann, Hagen;Golbik, Ralph P.;Ulbrich-Hofmann, Renate
尽管最近已经表明，未折叠的多肽链在从变性条件转移到天然条件时经历折叠，但是决定折叠形式的动力学和大小的力尚未被理解。在这里，我们使用单分子荧光共振能量转移实验上的小蛋白barstar的特点，在胍氯化物（GdmCl）和尿素的展开链。未折叠的蛋白质在降低变性剂浓度时折叠。低于3.5 M变性剂的临界浓度，GdmCl中的崩溃导致比尿素中更致密的状态。由于它是已知的GdmCl抑制静电相互作用，我们推断，库仑力是主导力量在未折叠barstar在原生条件下。通过在低尿素浓度下加入KCl使未折叠的芽孢杆菌RNA酶抑制剂压实的发现，清楚地支持了这一假设。(C)2007爱思唯尔有限公司保留所有权利。
Although it has been recently shown that unfolded polypeptide chains undergo a collapse on transfer from denaturing to native conditions, the forces determining the dynamics and the size of the collapsed form have not yet been understood. Here, we use single-molecule fluorescence resonance energy transfer experiments on the small protein barstar to characterize the unfolded chain in guanidinium chloride (GdmCl) and urea. The unfolded protein collapses on decreasing the concentration of denaturants. Below the critical concentration of 3.5 M denaturant, the collapse in GdmCl leads to a more dense state than in urea. Since it is known that GdmCl suppresses electrostatic interactions, we infer that Coulomb forces are the dominant forces acting in the unfolded barstar under native conditions. This hypothesis is clearly buttressed by the finding of a compaction of the unfolded barstar by addition of KCl at low urea concentrations. (C) 2007 Elsevier Ltd. All rights reserved.