The Effect of Charge-Charge Interactions on the Kinetics of α

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• 作者：Deguo Du ; Michelle R. Bunagan ; Feng Gai
• 刊名：Biophysical Journal
• 出版年：2007
• 出版时间：1 December 2007
• 年：2007
• 卷：93
• 期：11
• 页码：4076-4082
• 全文大小：184 K

文摘

The formation of the monomeric α-helix represents one of the simplest scenarios in protein folding; however, our current understanding of the folding dynamics of the α-helix motif is mainly based on studies of alanine-rich model peptides. To examine the effect of peptide sequence on the folding kinetics of α-helices, we studied the relaxation kinetics of a 21-residue helical peptide, Conantokin-T (Con-T), using time-resolved infrared spectroscopy in conjunction with a laser-induced temperature jump technique. Con-T is a neuroactive peptide containing a large number of charged residues that is found in the venom of the piscivorous cone snail Conus tulipa. The temperature-jump relaxation kinetics of Con-T is distinctly slower than that of previously studied alanine-based peptides, suggesting that the folding time of α-helices is sequence-dependent. Furthermore, it appears that the slower folding of Con-T can be attributed to the fact that its helical conformation is stabilized by charge-charge interactions or salt bridges. Although this finding contradicts an earlier molecular dynamics simulation, it also has implications for existing models of protein folding.