Regensburg 2019 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 9: Computational biophysics

BP 9.11: Vortrag

Dienstag, 2. April 2019, 12:30–12:45, H11

Optimized all-atom force fields for Mg²⁺ based on water exchange properties — •Kara K. Grotz and Nadine Schwierz — Department of Theoretical Biophysics, Max Planck Insitute of Biophysics, Frankfurt am Main, Germany

Magnesium cations are essential in many vital processes. Binding of a Mg²⁺ ion to the functional group on a biomolecule involves the removal of one water molecule from the first hydration shell. With the current force fields, this initial step takes about a microsecond. Hence, the description of binding events in a statistically meaningful way or the exploration of different binding sites of complex nucleic acids is beyond reach of Molecular Dynamics simulations. Here, we develop two improved Mg²⁺ force fields in combination with TIP3P water as required for many biomolecular simulations. For both models, we reproduce the experimental solvation free energy, the number of water molecules in the first hydration shell, their mean distance to the ²⁺ cation, and the diffusion coefficient. Modifying the Lorentz-Berthelot combination rules and using Kirkwood-Buff theory allows us to simultaneously reproduce the experimental activity derivatives. In addition, our first parameter set captures experimentally determined water exchange rates while the second parameter set enables us to accelerate the rate. Thereby, the second parameter set allows us to speed up simulations of binding events without changing thermodynamic properties.