%0 Journal Article
%T Impact of ¦Â-Turn Sequence on ¦Â-Hairpin Dynamics Studied with Infrared-Detected Temperature Jump
%A Alexander Popp
%A Ling Wu
%A Timothy A. Keiderling
%A Karin Hauser
%J Spectroscopy: An International Journal
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/102423
%X 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, SWTWETGKWTWK, 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, lower , with less change of the unfolding rate, , assuming two state behavior at higher temperatures.
%U http://www.hindawi.com/journals/spectroscopy/2012/102423/