Investigation on the Individual Contributions of N-H•••O=C and C-H•••O=C Interactions to the Binding Energies of β-Sheet Models

In this article, the binding energies of 16 antiparallel and parallel beta-sheet models are estimated using the analytic potential energy function we proposed recently and the results are compared with those obtained from MP2, AMBER99, OPLSAA/L, and CHARMM27 calculations. The comparisons indicate that the analytic potential energy function can produce reasonable binding energies for beta-sheet models. Further comparisons suggest that the binding energy of the beta-sheet models might come mainly from dipole-dipole attractive and repulsive interactions and VDW interactions between the two strands. The dipole-dipole attractive and repulsive interactions are further obtained in this article. The total of N-H center dot center dot center dot H-N and C=0 center dot center dot center dot O=C dipole-dipole repulsive interaction (the secondary electrostatic repulsive interaction) in file small ring of the antiparallel beta-sheet models is estimated to be about 6.0 kcal/mol. The individual N-H center dot center dot center dot O=C dipole-dipole attractive interaction is predicted to be -6.2 +/- 0.2 kcal/mol in the antiparallel beta-sheet models and -5.2 +- 0.6 kcal/mol in the parallel beta-sheet models. The individual C-alpha-H center dot center dot center dot O=C attractive interaction is -1.2 +/- 0.2 kcal/mol in the antiparallel beta-sheet models and -1.5 +- 0.2 kcal/mol in the parallel beta-sheet models. These values are important in understanding the interactions at protein-protein interfaces and developing a more accurate force field for peptides and proteins. (C) 2009 Wile), Periodicals, Inc. J Comput Chem 31: 1036-1044, 2010