Infrared Study of the Stability and Folding Kinetics of a Series of 尾-Hairpin Peptides with a Common NPDG Turn

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• 作者：Yao Xu ; Deguo Du ; Rolando Oyola
• 刊名：Journal of Physical Chemistry B
• 出版年：2011
• 出版时间：December 29, 2011
• 年：2011
• 卷：115
• 期：51
• 页码：15332-15338
• 全文大小：915K
• 年卷期：v.115,no.51(December 29, 2011)
• ISSN：1520-5207

文摘

The thermal stability and folding kinetics of a series of 15-residue 尾-hairpins with a common Type I [3:5] NPDG turn were studied using Fourier transform infrared spectroscopy (FTIR) and laser-induced temperature jump (T-jump) with infrared detection, respectively. Mutations at positions 3, 5, or 13 in the peptide sequence SEXYXNPDGTWTXTE, where X represents the position of mutation, were performed to study the roles of hydrophobic interactions in determining the thermodynamic and kinetic properties of 尾-hairpin folding. The thermal stability studies show a broad thermal folding/unfolding transition for all the peptides. T-jump studies indicate that these 尾-hairpin peptides fold in less than 2 渭s. In addition, both folding and unfolding rate constants decrease with increasing strength of hydrophobic interactions. Kinetically, the hydrophobic interactions have more significant influence on the unfolding rate than the folding rate. 桅-value analysis indicates that the hydrophobic interactions between the side chains are mainly formed at the latter part of the transition-state region during the folding process. In summary, the results suggest that the formation of the native structure of these 尾-hairpins depends on the correct topology of the hydrophobic cluster. Besides the formation of the turn region as a key process for folding as suggested by previous studies, a hydrophobic collapse process may also play a crucial role during 尾-hairpin folding.