1 – 4 kcal/mol
||Dill KA, Ozkan SB, Shell MS, Weikl TR. The protein folding problem. Annu Rev Biophys. 2008 37 :289-316. doi: 10.1146/annurev.biophys.37.092707.153558 p.291 right column top paragraphPubMed ID18573083
|| Byrne MP, Manuel RL, Lowe LG, Stites WE. 1995. Energetic contribution of side chain hydrogen bonding to the stability of staphylococcal nuclease. Biochemistry 34: 13949–60  Fersht AR, Shi JP, Knill-Jones J, Lowe DM, Wilkinson AJ, et al. 1985. Hydrogen bonding and biological specificity analysed by protein engineering. Nature 314: 235–38PubMed ID7577991, 3845322
||Studies of mutations
||P.291 right column top paragraph: "Hydrogen bonds among backbone amide and
carbonyl groups are key components of all secondary structures, and studies of mutations in different solvents estimate their strengths to be around 1–4 kcal/mol (primary sources) or stronger
(refs 5, 46). Similarly, tight packing in proteins implies that van der Waals interactions are important (ref 28)."