Strength of the C-H···O Hydrogen Bond of Amino Acid Residues
Journal of Biological Chemistry
American Society for Biochemistry and Molecular Biology
Although the peptide CαH group has historically not been thought to form hydrogen bonds within proteins, ab initio quantum calculations show it to be a potent proton donor. Its binding energy to a water molecule lies in the range between 1.9 and 2.5 kcal/mol for nonpolar and polar amino acids; the hydrogen bond (H-bond) involving the charged lysine residue is even stronger than a conventional OH··O interaction. The preferred H-bond lengths are quite uniform, about 3.32 Å. Formation of each interaction results in a downfield shift of the bridging hydrogen's chemical shift and a blue shift in the CαH stretching frequency, potential diagnostics of the presence of such an H-bond within a protein.
Scheiner, Steve; Kar, T.; and Gu, Y., "Strength of the C-H···O Hydrogen Bond of Amino Acid Residues" (2001). Chemistry and Biochemistry Faculty Publications. Paper 174.