Estimation on the intramolecular hydrogen-bonding energies in proteins and peptides by the analytic potential energy function

Computation of accurate intramolecular hydrogen-bonding energies in proteins and peptides is of great importance in understanding the conformational stabilities of peptides and developing a more accurate force field for proteins. In this paper, we apply the analytic potential energy function we proposed previously to estimate the intramolecular hydrogen-bonding energies in α-peptide and β-peptide conformers. The scheme is validated by applying it to four α-peptides and nine β-peptides. The estimated intramolecular hydrogen-bonding energies are in good agreement with those calculated by substitution method. The dipole-dipole interaction of the intramolecular N-H…OC hydrogen bond lie in the range of 6-8 kcal/mol and the dipole-dipole interaction of the Cα-H…OC hydrogen bond lie in the range of 1.5-1.8 kcal/mol. All of the results demonstrate that our scheme can simply and quickly yield reasonably correct intramolecular hydrogen-bonding energy in peptides.