Reaction pathway of proton transfer from the neutral to zwitterionic formsof amino acids. Support for a water molecule-mediated mechanism

The analysis of bond valences and precise neutron diffraction data taken fr om the Cambridge Structural Database were used to model the reaction path f or the proton transfer of amino acids. The correlations confirm the mechani sm with the support of water molecules mediating the proton transfer and al so show that intramolecular proton transfer is much less probable owing to the strains within amino acid molecules. A concept of the basicity and acid ity in the crystalline state is presented. Copyright (C) 2000 John Wiley & Sons, Ltd.