Temperature Dependence of Water Interactions with the Amide Carbonyls of 伪-Helices

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• 作者：Scott H. Brewer ; Yuefeng Tang ; Dung M. Vu ; S. Gnanakaran ; Daniel P. Raleigh ; R. Brian Dyer
• 刊名：Biochemistry
• 出版年：2012
• 出版时间：July 3, 2012
• 年：2012
• 卷：51
• 期：26
• 页码：5293-5299
• 全文大小：359K
• 年卷期：v.51,no.26(July 3, 2012)
• ISSN：1520-4995

文摘

Hydration is a key determinant of the folding, dynamics, and function of proteins. In this study, temperature-dependent Fourier transform infrared (FTIR) spectroscopy combined with singular value decomposition (SVD) and global fitting were used to investigate both the interaction of water with 伪-helical proteins and the cooperative thermal unfolding of these proteins. This methodology has been applied to an isolated 伪-helix (Fs peptide) and to globular 伪-helical proteins including the helical subdomain and full-length villin headpiece (HP36 and HP67). The results suggest a unique IR signature for the interaction of water with the helical amide carbonyl groups of the peptide backbone. The IR spectra indicate a weakening of the net hydrogen bond strength of water to the backbone carbonyls with increasing temperature. This weakening of the backbone solvation occurs as a discrete transition near the maximum of the temperature-dependent hydrophobic effect, not a continuous change with increasing temperature. Possible molecular origins of this effect are discussed with respect to previous molecular dynamics simulations of the temperature-dependent solvation of the helix backbone.