Pappenberger G, Aygün H, Engels J W, Reimer U, Fischer G, Kiefhaber T
Biozentrum der Universität Basel, Abteilung Biophysikalische Chemie, Klingelbergstrasse 70, CH-4056 Basel, Switzerland.
Nat Struct Biol. 2001 May;8(5):452-8. doi: 10.1038/87624.
Folding of tendamistat, an inhibitor of alpha-amylase, is a fast two-state process accompanied by two minor slow reactions, which were assigned to prolyl isomerization. In a proline-free variant, 5% of the molecules still fold slowly with a rate constant of 2.5 s(-1). This reaction is caused by a slow equilibrium between two populations of unfolded molecules. The time constant for this equilibration process, its sensitivity to LiCl and its temperature dependence identify it as a cis-trans isomerization of nonprolyl peptide bonds. Although nonprolyl peptide bonds have the cis conformation populating only approximately 0.15% in unfolded proteins, their large number generates a significant fraction of slow-folding molecules. This emphasizes that heterogeneous populations in an unfolded protein can induce complex folding kinetics on various time scales.
α-淀粉酶抑制剂腱糖淀粉酶的折叠是一个快速的两态过程，伴有两个较小的慢反应，这两个慢反应被认为是脯氨酰异构化。在一个无脯氨酸变体中，5%的分子仍以2.5 s⁻¹的速率常数缓慢折叠。该反应是由未折叠分子的两个群体之间的缓慢平衡引起的。这个平衡过程的时间常数、其对LiCl的敏感性及其温度依赖性将其确定为非脯氨酰肽键的顺反异构化。尽管非脯氨酰肽键在未折叠蛋白质中的顺式构象仅约占0.15%，但它们的数量众多，产生了相当一部分慢折叠分子。这强调了未折叠蛋白质中的异质群体可以在不同时间尺度上诱导复杂的折叠动力学。
