A new force field (ECEPP-05) for peptides, proteins, and organic molecules

Area of Science:

• Computational Chemistry
• Molecular Modeling
• Biophysics

Background:

• Accurate molecular mechanics force fields are crucial for simulating organic molecules and peptides.
• Existing force fields may require refinement for specific applications, necessitating the development of new parameter sets.

Purpose of the Study:

• To parametrize and test a novel all-atom force field for organic molecules and peptides.
• To ensure the accurate representation of conformational energies and structural properties.

Main Methods:

• Determined 1-4 nonbonded and electrostatic scale factors using six model organic molecules.
• Derived partial atomic charges by fitting to quantum-mechanical electrostatic potentials (HF/6-31G).
• Computed torsional parameters by fitting to ab initio rotational energy profiles (MP2/6-31G).

Main Results:

• Multiple-conformation-derived charges and a scale factor of 1.0 for 1-4 interactions yielded the best agreement with ab initio data.
• Torsional parameters for organic molecules showed high accuracy with average errors < 0.2 kcal/mol.
• The force field accurately reproduced peptide conformational energy maps and crystal structures.

Conclusions:

• The developed all-atom force field demonstrates high accuracy for organic molecules and peptides.
• The force field's transferability and performance were validated through simulations of peptides.
• This new force field is suitable for accurate molecular simulations in computational chemistry and biophysics.