STRENGTH OF HYDROGEN-BONDS IN ALPHA-HELICES

The intramolecular helix backbone > C=O - - - H-N < hydrogen bonding e nergies in poly(L-alanine) alpha helices have been estimated both in v acuum and in an aqueous environment using the parameter sets of five o f the most commonly used force fields for modeling biomolecules, namel y AMBER, CHARMM, ECEPP, GROMOS, and OPLS. The relative capabilities of these force fields in describing the H-bonding interactions with diff erent dielectric continuum models have been assessed. A modified Hinge rty-Lavery function is proposed for the treatment of electrostatic int eractions of biomolecules in an aqueous environment. The helix backbon e H-bonding energies predicted by this function (similar to -1 kcal/mo l) correspond closely with the experiment. (C) 1997 by John Wiley & So ns, Inc.