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Multiple-site titration and molecular modeling: two rapid methods for computing energies and forces for ionizable
1Department of Chemistry, University of Houston, Texas 77204-5641.
Proteins
|March 1, 1993
Summary
Neglecting ionization changes in protein computer models causes significant errors. New methods accurately calculate these effects with minimal computational cost, enabling their use in complex simulations.
Area of Science:
- Computational Biology
- Biophysics
- Biochemistry
Background:
- Protein modeling often uses simplified electrostatic models for ionizable groups.
- Ignoring ionization state changes can lead to substantial inaccuracies in energy calculations.
Purpose of the Study:
- To evaluate the validity of purely electrostatic approximations in protein models.
- To develop computationally efficient methods for accurately treating ionizable groups in proteins.
Main Methods:
- Developed two novel methods to address computational challenges of ionizable groups.
- Method 1: Approximates energies by calculating the free energy of a single dominant ionization state.
- Method 2: Clusters ionizable groups, treating intracluster interactions exactly and intercluster interactions approximately.
Main Results:
- Both methods demonstrated good performance on proteins with up to 123 ionizable groups.
- The rapid method achieved results in 0.01–0.34 seconds.
- The accurate method yielded results in 0.7–15 seconds, providing accurate energies and fractional charges.
Conclusions:
- The developed methods significantly reduce computational cost for modeling ionization.
- These techniques may allow the integration of ionization effects into iterative computations like energy minimization and conformational searches.