Intramolecular and Water Mediated Tautomerism of Solvated Glycine

Understanding
tautomerism and characterizing solvent
effects on
the dynamic processes pose significant challenges. Using enhanced-sampling
molecular dynamics based on state-of-the-art deep learning potentials,
we investigated the tautomeric equilibria of glycine in water. We
observed that the tautomerism between neutral and zwitterionic glycine
can occur through both intramolecular and intermolecular proton transfers.
The latter proceeds involving a contact anionic-glycine–hydronium
ion pair or separate cationic-glycine–hydroxide ion pair. These
pathways with comparable barriers contribute almost equally to the
reaction flux.