Evidence of an Unusual N鈥揌路路路N Hydrogen Bond in Proteins

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• 作者：Ramkrishna Adhikary ; J枚rg Zimmermann ; Jian Liu ; Ryan P. Forrest ; Tesia D. Janicki ; Philip E. Dawson ; Steven A. Corcelli ; Floyd E. Romesberg
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：October 1, 2014
• 年：2014
• 卷：136
• 期：39
• 页码：13474-13477
• 全文大小：260K
• ISSN：1520-5126

文摘

Many residues within proteins adopt conformations that appear to be stabilized by interactions between an amide N鈥揌 and the amide N of the previous residue. To explore whether these interactions constitute hydrogen bonds, we characterized the IR stretching frequencies of deuterated variants of proline and the corresponding carbamate, as well as the four proline residues of an Src homology 3 domain protein. The C_未D₂ stretching frequencies are shifted to lower energies due to hyperconjugation with N_i electron density, and engaging this density via protonation or the formation of the N_i+1鈥揌路路路N_i interaction ablates this hyperconjugation and thus induces an otherwise difficult to explain blue shift in the C鈥揇 absorptions. Along with density functional theory calculations, the data reveal that the N_i+1鈥揌路路路N_i interactions constitute H-bonds and suggest that they may play an important and previously underappreciated role in protein folding, structure, and function.