The kinetics of conformational fluctuations in an unfolded protein measured by fluorescence methods
The kinetics of conformational fluctuations in an unfolded protein measured by fluorescence methods
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DOI：
10.1073/pnas.0500127102
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发表时间：
2005-02-15
影响因子：
11.1
通讯作者：
Frieden, C
中科院分区：
文献类型：
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作者：
Chattopadhyay, K;Elson, EL;Frieden, C
未折叠蛋白质最简单的动力学模型是一个统计卷曲，它不断经历大量的构象波动。越来越多的研究表明，未折叠的蛋白质不是简单的无规卷曲，而是形成瞬时结构。我们已经直接测量未折叠的肠脂肪酸结合蛋白（131 aa，15 kDa）的构象波动率，通过使用荧光自猝灭结合荧光相关光谱。在此状态下的构象波动具有表观弛豫时间τ（R），在pH 7和20 ℃的3M盐酸胍中为1.6 μ sec。τ（R）的值随溶液粘度的增加而增加，表明扩散过程。在pH 2的熔融球状态下，τ（R）为2.5 μ sec，随着盐诱导的二级结构的形成而进一步增加。这些测量，这应该是广泛适用于其他系统，可以提供重要的信息，仍然不完全了解未折叠的蛋白质的构象特性和蛋白质折叠的机制。
The simplest dynamic model for an unfolded protein is a statistical coil that continually undergoes substantial conformational fluctuations. A growing number of studies indicate that the unfolded protein is not a simple random coil but rather forms transient structures. We have directly measured the rate of conformational fluctuations of unfolded intestinal fatty acid binding protein (131 aa, 15 kDa) by using fluorescence self-quenching in combination with fluorescence correlation spectroscopy. The conformational fluctuations in this state have an apparent relaxation time, tau(R), Of 1.6 musec in 3 M guanidine-HCl at pH 7 and 20degreesC. The value Of tau(R) increases with increasing solution viscosity, suggesting a diffusive process. in the molten globule state at pH 2, tau(R) is 2.5 musec, increasing further with the formation of salt-induced secondary structure. These measurements, which should be widely applicable to other systems, can provide important information about the still incompletely understood conformational properties of unfolded proteins and the mechanism of protein folding.