We report on the calculation of absolute acidity constants of amino acid side chain and backbone groups using a recently introduced density functional based molecular dynamics (DFMD) simulation technique [Sulpizi and Sprik, Phys. Chem. Chem. Phys. 10, 2008]. Free energy differences are obtained from the vertical energy gaps between protonated and deprotonated states through removal or insertion of a proton. The proton position for insertion is determined by a dummy proton kept in place by a harmonic potential. The accuracy of our approach is � 2 pKa units, which is the accuracy expected for DFT. This study is an important first step in the development of a more rigorous pKa value calculation of amino acids in proteins.Moreover, the solvation structures obtained from DFMD may serve as a benchmark for force field or continuum model development.

Acidity constants and solvation structures of amino acids via DFTMD

240th National Meeting (2010)

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