Kinetics of unfolding and folding from amide hydrogen exchange in native ubiquitin
Kinetics of unfolding and folding from amide hydrogen exchange in native ubiquitin
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DOI：
10.1038/86208
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发表时间：
2001-04-01
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影响因子：
--
通讯作者：
Robertson, AD
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文献类型：
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作者：
Sivaraman, T;Arrington, CB;Robertson, AD
酰胺氢（NH）交换是为数不多的实验技术之一，具有确定天然蛋白质中几乎每个残基构象运动的热力学和动力学的潜力。NH交换的分子运动方面的定量解释依赖于一个简单的两态动力学模型：在任何给定的缓慢交换NH，一个封闭的或交换不合格的构象是在平衡与开放或交换合格的构象。以前的研究已经证明了这个模型在测量构象平衡的准确性，通过比较交换数据与蛋白质展开的热力学。我们在这里报告的准确性的模型在确定天然蛋白质的构象变化的动力学测试。折叠和展开的动力学的泛素已被测量的常规方法和比较与那些来自一个全面的分析的pH值依赖性的交换在本地泛素。从这两个非常不同类型的实验折叠和展开的速率常数显示出良好的一致性。因此，NH交换的简单模型似乎是一个强大的框架，用于获得有关天然蛋白质分子运动的定量信息。
Amide hydrogen (NH) exchange is one of the few experimental techniques with the potential for determining the thermodynamics and kinetics of conformational motions at nearly every residue in native proteins. Quantitative interpretation of NH exchange in terms of molecular motions relies on a simple two-state kinetic model: at any given slowly exchanging NH, a closed or exchange-incompetent conformation is in equilibrium with an open or exchange-competent conformation. Previous studies have demonstrated the accuracy of this model in measuring conformational equilibria by comparing exchange data with the thermodynamics of protein unfolding. We report here a test of the accuracy of the model in determining the kinetics of conformational changes in native proteins. The kinetics of folding and unfolding for ubiquitin have been measured by conventional methods and compared with those derived from a comprehensive analysis of the pH dependence of exchange in native ubiquitin. Rate constants for folding and unfolding from these two very different types of experiments show good agreement. The simple model for NH exchange thus appears to be a robust framework for obtaining quantitative information about molecular motions in native proteins.