SwissParam

SwissParam provides topology and force field parameters for small organic molecules to enable CHARMM-compatible molecular dynamics simulations and ligand binding energy estimation in structure-based drug discovery.

Key Features:

• Force field generation: Generates topologies and parameter sets for arbitrary small organic molecules by translating the Merck Molecular Force Field (MMFF) into parameters compatible with the CHARMM all-atom force field.
• Integration with docking software: Produces outputs used directly by docking programs such as EADock2 and EADock DSS for ligand-protein docking, with reported docking success rates between 56% and 78%.
• Rapid binding free energy estimation: Supports a rapid binding free energy estimation approach using SwissParam ligand parameters together with CHARMM22/27 protein parameters, requiring minimal minimization and reproducing experimental binding free energies across 214 ligand-protein complexes involving 62 proteins (standard error 2.0 kcal/mol, R = 0.74).

Scientific Applications:

• Structure-based drug design: Parameterizes small-molecule ligands for incorporation into CHARMM-based structure-based drug design workflows.
• Ligand-protein docking simulations: Provides ligand descriptions for docking simulations with programs such as EADock2 and EADock DSS to evaluate binding poses and ranks.
• Binding free energy calculations: Enables rapid estimation of ligand-protein binding free energies using generated ligand parameters alongside CHARMM22/27 protein parameters.

Methodology:

SwissParam translates MMFF-derived parameters into a CHARMM-compatible format to generate topology and parameter files for small organic molecules, outputs compatible with CHARMM and GROMACS, and supports a rapid binding free energy estimation protocol using ligand parameters and CHARMM22/27 protein parameters with minimal minimization.