Strength of hydrogen bonds in helices

> < ABSTRACT: The intramolecular helix backbone C O H— N hydrogen Ž . bonding energies in poly L-alanine a helices have been estimated both in vacuum and in an aqueous environment using the parameter sets of five of the most commonly used force fields for modeling biomolecules, namely AMBER, CHARMM, ECEPP, GROMOS, and OPLS. The relative capabilities of these force fields in describing the H-bonding interactions with different dielectric continuum models have been assessed. A modified Hingerty]Lavery function is proposed for the treatment of electrostatic interactions of biomolecules in an aqueous environment. The helix backbone H-bonding energies predicted by this Ž . function ; y1 kcalrmol correspond closely with the experiment. Q 1997 by John Wiley & Sons, Inc. J Comput Chem 18: 1245]1252, 1997