| Autor: |
Koca Fındık B; Department of Chemistry, Bogazici University, Bebek, Istanbul 34342, Turkey., Jafari M; Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, United States., Song LF; Biochemical and Biophysical Systems Group, Lawrence Livermore National Laboratory, Livermore, California 94550, United States., Li Z; Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States., Aviyente V; Department of Chemistry, Bogazici University, Bebek, Istanbul 34342, Turkey., Merz KM Jr; Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, United States.; Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States. |
| Abstrakt: |
Phosphate derivatives and their interaction with metal cations are involved in many important biological phenomena, so an accurate characterization of the phosphate-metal interaction is necessary to properly understand the role of phosphate-metal contacts in mediating biological function. Herein, we improved the standard 12-6 Lennard-Jones (LJ) potential via the usage of the 12-6-4 LJ model, which incorporates ion-induced dipole interactions. Via parameter scanning, we fine-tuned the 12-6-4 LJ polarizability values to obtain accurate absolute binding free energies for the phosphate anions H 2 PO 4 - , HPO 4 2- , PO 4 3- coordinating with Ca 2+ and Mg 2+ . First, we modified the phosphate 12-6-4 LJ parameters to reproduce the solvation free energies of the series of phosphate anions using the thermodynamic integration (TI) method. Then, using the potential mean force (PMF) method, the polarizability of the metal-phosphate interaction was obtained. We show that the free energy profiles of phosphate ions coordinated to Ca 2+ and Mg 2+ generally show similar trends at longer metal-phosphate distances, while the absolute binding energy values increased with deprotonation. The resulting parameters demonstrate the flexibility of the 12-6-4 LJ-type nonbonded model and its usefulness in accurately describing cation-anion interactions. |
