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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >SUBMILLISECOND PROTEIN FOLDING KINETICS STUDIED BY ULTRARAPID MIXING
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SUBMILLISECOND PROTEIN FOLDING KINETICS STUDIED BY ULTRARAPID MIXING

机译：超快速混合研究的次要蛋白质折叠动力学

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An ultrarapid-mixing continuous-flow method has been developed to study submillisecond folding of chemically denatured proteins, Turbulent flow created by pumping solutions through a small gap dilutes the denaturant in tens of microseconds, We have used this method to study cytochrome c folding kinetics in the previously inaccessible time range 80 mu s to 3 ms, To eliminate the heme-ligand exchange chemistry that complicates and slows the folding kinetics by trapping misfolded structures, measurements were made with the imidazole complex. Fluorescence quenching due to excitation energy transfer from the tryptophan to the heme was used to monitor the distance between these groups, The fluorescence decrease is biphasic. There is an unresolved process with tau < 50 mu s, followed by a slower, exponential process with tau = 600 mu s at the lowest denaturant concentration (0.2 M guanidine hydrochloride). These kinetics are interpreted as a barrier-free, partial collapse to the new equilibrium unfolded state at the lower denaturant concentration, followed by stower crossing of a free energy barrier separating the unfolded and folded states, The results raise several fundamental issues concerning the dynamics of collapse and barrier crossings in protein folding. [References: 54]
机译：已开发出一种超快速混合连续流方法来研究化学变性蛋白质的亚毫秒级折叠，通过将溶液泵入一个小缝隙而产生的湍流会在数十微秒内将变性剂稀释，我们已使用此方法来研究细胞色素c的折叠动力学。以前无法访问的时间范围是80毫秒至3毫秒，为消除血红素-配体交换化学过程（通过捕获错折叠的结构而使其复杂化并减慢折叠动力学），对咪唑配合物进行了测量。由于激发能量从色氨酸转移到血红素而导致的荧光猝灭被用来监测这些基团之间的距离。荧光的减少是双相的。有一个tau <50μs的未解决过程，然后是在最低变性剂浓度（0.2 M盐酸胍）下tau = 600μs的较慢的指数过程。这些动力学被解释为在较低的变性剂浓度下无障​​碍，部分塌陷到新的平衡未折叠状态，然后通过自由能垒的较下交叉而分离了未折叠状态和折叠状态。结果提出了一些与动力学有关的基本问题。折叠和蛋白质折叠中的屏障交叉。 [参考：54]

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