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 alpha-peptide and beta-peptide conformers. The scheme is validated by applying it to four a-peptides and nine beta-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 center dot center dot center dot O=C hydrogen bond lie in the range of 6-8 kcal/mol and the dipole-dipole interaction of the C-alpha-H center dot center dot center dot O=C 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. (C) 2010 Elsevier B.V. All rights reserved.