Identification of Spectroscopic Patterns of CH···O H-Bonds in Proteins

Document Type

Article

Journal/Book Title

Journal of Physical Chemistry B

Publication Date

2009

Publisher

American Chemical Society

Volume

113

Issue

30

First Page

10421

Last Page

10427

Abstract

Ab initio calculations are used to identify characteristics of vibrational and NMR spectra that signal the involvement of a protein backbone in a CH···O H-bond and that distinguish this sort of interaction from other H-bonds in which a protein might participate. Glycine and alanine dipeptides, in both their C7 and C5 minimum-energy structures, are paired with formamide in a number of different H-bonding arrangements. The CH···O H-bond is characterized by a small contraction of the C−H bond length, along with a blue shift in its stretching frequency, accompanied by an intensification of this vibrational band. In the context of NMR spectra, the bridging CH proton’s chemical shift is moved downfield by 1−2 ppm. The aforementioned features are not produced by other H-bonds in which the protein backbone might participate, such as NH proton donation or accepting a proton via the peptide C═O.

Comments

Originally published by American Chemical Society in the Journal of Physical Chemistry.

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