Impact of β-Turn Sequence on β-Hairpin Dynamics Studied with Infrared-Detected Temperature Jump. Issue 5 (11th July 2012)

• Record Type: Journal Article
• Authors: Popp Popp, Alexander Alexander; Wu Wu, Ling Ling; Keiderling Keiderling, Timothy A. Timothy A.; Hauser Hauser, Karin Karin
• Is Part Of: Spectroscopy. Volume 27:Issue 5/6(2012)
• Page Start: 557
• Page End: 564
• Publication Date: 2012-07-11
• Subjects: Hairpin peptide -- tryptophan -- tryptophan zipper -- temperature jump kinetics -- β-turn -- infrared spectroscopy
• DOI: 10.1155/2012/102423
• Languages: English
• ISSNs: 0712-4813

Abstract

Abstract : Folding dynamics for β -structure loss and disordered structure gain were studied in a model β -hairpin peptide based on Cochran's tryptophan zipper peptide Trpzip2, but with an altered Thr-Gly (TG) turn sequence, that is, SWTWETG KWTWK, using laser-induced temperature-jump (T-jump) kinetics with IR detection. As has been shown previously, the TG turn sequence reduces the thermodynamic β -hairpin stability as compared to the Asn-Gly sequence used in Trpzip2 (TZ2-NG). In this study, we found that the TG-turn slows down the overall relaxation dynamics as compared to TZ2-NG, which were studied at higher temperatures where the time constants show little difference between relaxation of the β -strand and the disordered conformation. These time constants become equivalent at lower temperatures for TZ2-TG than was seen for TZ2-NG. The correlation of thermodynamic stability and rates of relaxation suggests that the change from NG to TG turn results in a slowing of folding, lowerk f, with less change of the unfolding rate, k u, assuming two state behavior at higher temperatures.