Strength of the Calpha H..O hydrogen bond of amino acid residues |
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Authors: | Scheiner S Kar T Gu Y |
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Institution: | Department of Chemistry and Biochemistry, Utah State University, Logan 84322-0300, USA. scheiner@cc.usu.edu |
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Abstract: | Although the peptide C(alpha)H 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 A. Formation of each interaction results in a downfield shift of the bridging hydrogen's chemical shift and a blue shift in the C(alpha)H stretching frequency, potential diagnostics of the presence of such an H-bond within a protein. |
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