Molecular dynamics simulations within the density functional-molecular mechanics approach are used to investigate amino acid chemistry in aqueous solution. Equilibrium solvation effects are studied in both the neutral and zwitterionic forms of the glycine. Dynamic solvent effects on amino acid reactions in water are illustrated through the simulation of the fast conversion of neutral glycine to its zwitterionic form. The different factors contributing to the intramolecular proton transfer are analyzed from a dynamic point of view.