Identification of spectroscopic patterns of CH...O H-bonds in proteins.
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.
Scheiner
Steve
S
Department of Chemistry & Biochemistry, Utah State University, Logan, Utah 84322-0300, USA. steve.scheiner@usu.edu
D004151:Dipeptides / Q000737:chemistry; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*; D011522:Protons
D004151:Dipeptides; D011506:Proteins; D011522:Protons