Chang Jui-Yoa, Lu Bao-Yuan, Li Li
Center for Protein Chemistry, Brown Foundation Institute of Molecular Medicine for the Prevention of Human Diseases, University of Texas, Houston, TX 77030, USA.
Anal Biochem. 2005 Jul 1;342(1):78-85. doi: 10.1016/j.ab.2005.03.038. Epub 2005 Apr 9.
The conformations of native proteins are in principle, and in most cases, dictated by the law of thermodynamics. Accordingly, a native protein must always exist in equilibrium with a minor concentration of nonnative (denatured) conformational isomers even at nondenaturing conditions. The presence of an infinitesimal quantity of nonnative conformational isomers at physiological conditions is biologically relevant due to their propensity to aggregate, which is an underlying cause of many neurodegenerative diseases. However, their detection and quantification are inherently difficult. In this article, we describe a simple strategy using the technique of disulfide scrambling to identify and quantify such minute concentrations of nonnative isomers. It is demonstrated that even for small stable proteins such as epidermal growth factor and hirudin, approximately 1% of heterogeneous nonnative isomers coexist with the native proteins under physiological conditions.
天然蛋白质的构象原则上，并且在大多数情况下，由热力学定律决定。因此，即使在非变性条件下，天然蛋白质也必须始终与少量非天然（变性）构象异构体处于平衡状态。在生理条件下存在极少量的非天然构象异构体具有生物学相关性，因为它们易于聚集，这是许多神经退行性疾病的根本原因。然而，对它们的检测和定量本质上是困难的。在本文中，我们描述了一种使用二硫键重排技术来鉴定和定量此类微量非天然异构体的简单策略。结果表明，即使对于诸如表皮生长因子和水蛭素等小的稳定蛋白质，在生理条件下约1%的异质非天然异构体也与天然蛋白质共存。
