Development of a ReaxFF reactive force field for glycine and application to solvent effect and tautomerization

Obaidur Rahaman, Adri C.T. Van Duin, William A. Goddard, Douglas J. Doren

Research output: Contribution to journalArticle

115 Citations (Scopus)

Abstract

Tautomerization of amino acids between the neutral form (NF) and the zwitterionic form (ZW) in water has been extensively studied, often using glycine as a model to understand this fundamental process. In spite of many advanced studies, the tautomerization reaction remains poorly understood because of the intrinsic complexities of the system, including multiple accessible reaction pathways, charge transfer, and variations of solvation structure. To establish an accurate model that can be used for molecular dynamics simulations, a ReaxFF reactive force field has been developed for glycine. A training set for the ReaxFF hydrocarbon potential was augmented with several glycine conformers and glycine-water complexes. The force field parameters were optimized to reproduce the quantum mechanically derived energies of the species in the training set. The optimized potential could accurately describe the properties of gas-phase glycine. It was applied to investigate the effect of solvation on the conformational distribution of glycine. Molecular dynamics simulations indicated significant differences in the dominant conformers in the gas phase and in water. This suggests that the tautomerization of glycine occurs through a conformational isomerization followed by the proton transfer event. The direct reaction mechanism of the NF → ZW proton transfer reaction in water, as well as mechanisms mediated by one or two water molecules, were investigated using molecular dynamics simulations. The results suggest that the proton transfer reaction is most likely mediated by a single water molecule. The ReaxFF potential developed in this work provides an accurate description of proton transfer in glycine and thus provides a useful methodology for simulating proton transfer reactions in organic molecules in the aqueous environment.

Original languageEnglish (US)
Pages (from-to)249-261
Number of pages13
JournalJournal of Physical Chemistry B
Volume115
Issue number2
DOIs
StatePublished - Jan 20 2011

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glycine
Glycine
field theory (physics)
Amino acids
Proton transfer
Water
protons
water
Molecular dynamics
Solvation
molecular dynamics
Molecules
solvation
Computer simulation
education
Gases
vapor phases
molecules
simulation
Isomerization

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

Cite this

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title = "Development of a ReaxFF reactive force field for glycine and application to solvent effect and tautomerization",
abstract = "Tautomerization of amino acids between the neutral form (NF) and the zwitterionic form (ZW) in water has been extensively studied, often using glycine as a model to understand this fundamental process. In spite of many advanced studies, the tautomerization reaction remains poorly understood because of the intrinsic complexities of the system, including multiple accessible reaction pathways, charge transfer, and variations of solvation structure. To establish an accurate model that can be used for molecular dynamics simulations, a ReaxFF reactive force field has been developed for glycine. A training set for the ReaxFF hydrocarbon potential was augmented with several glycine conformers and glycine-water complexes. The force field parameters were optimized to reproduce the quantum mechanically derived energies of the species in the training set. The optimized potential could accurately describe the properties of gas-phase glycine. It was applied to investigate the effect of solvation on the conformational distribution of glycine. Molecular dynamics simulations indicated significant differences in the dominant conformers in the gas phase and in water. This suggests that the tautomerization of glycine occurs through a conformational isomerization followed by the proton transfer event. The direct reaction mechanism of the NF → ZW proton transfer reaction in water, as well as mechanisms mediated by one or two water molecules, were investigated using molecular dynamics simulations. The results suggest that the proton transfer reaction is most likely mediated by a single water molecule. The ReaxFF potential developed in this work provides an accurate description of proton transfer in glycine and thus provides a useful methodology for simulating proton transfer reactions in organic molecules in the aqueous environment.",
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Development of a ReaxFF reactive force field for glycine and application to solvent effect and tautomerization. / Rahaman, Obaidur; Van Duin, Adri C.T.; Goddard, William A.; Doren, Douglas J.

In: Journal of Physical Chemistry B, Vol. 115, No. 2, 20.01.2011, p. 249-261.

Research output: Contribution to journalArticle

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