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Constant-pH Simulations with the Polarizable Atomic Multipole AMOEBA Force Field
Journal article   Open access   Peer reviewed

Constant-pH Simulations with the Polarizable Atomic Multipole AMOEBA Force Field

Andrew C Thiel, Matthew J Speranza, Sanika Jadhav, Lewis L Stevens, Daniel K Unruh, Pengyu Ren, Jay W Ponder, Jana Shen and Michael J Schnieders
Journal of chemical theory and computation, Vol.20(7), pp.2921-2933
03/20/2024
DOI: 10.1021/acs.jctc.3c01180
PMCID: PMC11008096
PMID: 38507252
url
https://doi.org/10.1021/acs.jctc.3c01180View
Published (Version of record) Open Access

Abstract

Accurately predicting protein behavior across diverse pH environments remains a significant challenge in biomolecular simulations. Existing constant-pH molecular dynamics (CpHMD) algorithms are limited to fixed-charge force fields, hindering their application to biomolecular systems described by permanent atomic multipoles or induced dipoles. This work overcomes these limitations by introducing the first polarizable CpHMD algorithm in the context of the Atomic Multipole Optimized Energetics for Biomolecular Applications (AMOEBA) force field. Additionally, our implementation in the open-source Force Field X (FFX) software has the unique ability to handle titration state changes for crystalline systems including flexible support for all 230 space groups. The evaluation of constant-pH molecular dynamics (CpHMD) with the AMOEBA force field was performed on 11 crystalline peptide systems that span the titrating amino acids (Asp, Glu, His, Lys, and Cys). Titration states were correctly predicted for 15 out of the 16 amino acids present in the 11 systems, including for the coordination of Zn by cysteines. The lone exception was for a HIS-ALA peptide where CpHMD predicted both neutral histidine tautomers to be equally populated, whereas the experimental model did not consider multiple conformers and diffraction data are unavailable for rerefinement. This work demonstrates the promise polarizable CpHMD simulations for p predictions, the study of biochemical mechanisms such as the catalytic triad of proteases, and for improved protein-ligand binding affinity accuracy in the context of pharmaceutical lead optimization.
Molecular structure Monomers Peptides and proteins Reaction mechanisms Titration UIOWA OA Agreement

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