What happens to salt-bridges in nonaqueous environments: Insights from quantum mechanics calculations

Zheng, Y J; Ornstein, R L

doi:10.1021/ja960041o

Title: What happens to salt-bridges in nonaqueous environments: Insights from quantum mechanics calculations

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Abstract

To examine he effect of solvent environment on protein salt-bridges, we performed high-level ab initio molecular orbital calculations in the gas phase and in three different solvents on a salt-bridge as modeled by formate and gaunidinium ions. The energy difference between the neutral hydrogen-bonded complex and the zwitterionic form and the interconversion barrier between them are investigated in detail at RHF/6-31G{sup *}, RHF/6-311+G{sup **}, MP2/6-31G{sup *}, and MP2/6-311+G{sup **} levels. In the gas phase, the neutral conventional hydrogen-bonded complex is predicted to be favored at all four levels of theory and there is a small barrier for the interconversion. In a nonpolar, hydrophobic solvent like CCl{sup 4}, the energy difference between these two forms is small and the barrier that separates them is also low, but the neutral hydrogen-bonded complex still seems to be slightly favored. However, in polar solvents like DMSO and water, the zwitterionic form becomes much more favored. In polar solvents, the barrier for conversion of the neutral hydrogen-bonded form to the zwitterionic form is small at the Hartree-Fock level, but it disappears at the correlated level (MP2). The implication of these findings toward stabilizing an enzyme in nonaqueous solvents is briefly discussed. 55 refs., 1 fig.,more » 6 tabs.« less

Authors:

Zheng, Y J; Ornstein, R L ^[1]

Pacific Northwest National Lab., Richland, WA (United States)

Publication Date:: Wed Nov 13 00:00:00 EST 1996

OSTI Identifier:: 426236

DOE Contract Number:: AC06-76RL01830

Resource Type:: Journal Article

Journal Name:: Journal of the American Chemical Society

Additional Journal Information:: Journal Volume: 118; Journal Issue: 45; Other Information: PBD: 13 Nov 1996

Country of Publication:: United States

Language:: English

Subject:: 55 BIOLOGY AND MEDICINE, BASIC STUDIES; 40 CHEMISTRY; 66 PHYSICS; PROTEINS; MATHEMATICAL MODELS; QUANTUM MECHANICS; MOLECULAR ORBITAL METHOD; HYDROGEN; SALTS; CHEMICAL BONDS; COMPLEXES; ENZYMES; STABILITY; WATER; SOLVENTS; MOLECULAR STRUCTURE; NUMERICAL DATA

Citation Formats


                    Zheng, Y J, and Ornstein, R L. What happens to salt-bridges in nonaqueous environments: Insights from quantum mechanics calculations.  United States: N. p., 1996. 
        Web.  doi:10.1021/ja960041o.

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                    Zheng, Y J, & Ornstein, R L. What happens to salt-bridges in nonaqueous environments: Insights from quantum mechanics calculations.  United States.  https://doi.org/10.1021/ja960041o

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                    Zheng, Y J, and Ornstein, R L. 1996.  
        "What happens to salt-bridges in nonaqueous environments: Insights from quantum mechanics calculations".  United States.  https://doi.org/10.1021/ja960041o.

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@article{osti_426236,

  title        = {What happens to salt-bridges in nonaqueous environments: Insights from quantum mechanics calculations},

  author       = {Zheng, Y J and Ornstein, R L},

  abstractNote = {To examine he effect of solvent environment on protein salt-bridges, we performed high-level ab initio molecular orbital calculations in the gas phase and in three different solvents on a salt-bridge as modeled by formate and gaunidinium ions. The energy difference between the neutral hydrogen-bonded complex and the zwitterionic form and the interconversion barrier between them are investigated in detail at RHF/6-31G{sup *}, RHF/6-311+G{sup **}, MP2/6-31G{sup *}, and MP2/6-311+G{sup **} levels. In the gas phase, the neutral conventional hydrogen-bonded complex is predicted to be favored at all four levels of theory and there is a small barrier for the interconversion. In a nonpolar, hydrophobic solvent like CCl{sup 4}, the energy difference between these two forms is small and the barrier that separates them is also low, but the neutral hydrogen-bonded complex still seems to be slightly favored. However, in polar solvents like DMSO and water, the zwitterionic form becomes much more favored. In polar solvents, the barrier for conversion of the neutral hydrogen-bonded form to the zwitterionic form is small at the Hartree-Fock level, but it disappears at the correlated level (MP2). The implication of these findings toward stabilizing an enzyme in nonaqueous solvents is briefly discussed. 55 refs., 1 fig., 6 tabs.},

  doi          = {10.1021/ja960041o},

  url          = {https://www.osti.gov/biblio/426236},
  journal      = {Journal of the American Chemical Society},
number       = 45,

  volume       = 118,

  place        = {United States},

  year         = {Wed Nov 13 00:00:00 EST 1996},

  month        = {Wed Nov 13 00:00:00 EST 1996}

}

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