| Popis: |
It is shown that an understanding of some key biological processes such as the thermodynamics of enzyme-ligand binding or the selectivity of ion-channels is ultimately dependent on an understanding of the details of ion hydration. Therefore, a model for calculating the hydration free energy of ions in aqueous solvent is presented. The model is used to first calculate the proton hydration free energy, ΔGhyd(H+), in an effort to resolve the uncertainty concerning its exact value. In the model we define ΔGhyd(H+) as the free energy change associated with the following process: ΔG{H+(gas)+[H2O]n(aq)→H+[H2O]n)(aq)}, where the solvent is represented by a neutral n-water cluster embedded in a dielectric continuum and the solvated proton is represented by a protonated n-water cluster also in the continuum. All solvated species are treated as quantum mechanical solutes (B3LYP, MP2, MP4, CCSD(T)) coupled to a dielectric continuum using a self consistent reaction field (SCRF) cycle. An investigation of the behavior ... |
