We show that the hybrid quantum mechanical/effective fragment potential (QM/EFP) can be a very effective and practical quantum mechanical molecular dynamics method, when it is properly combined with well-developed traditional molecular dynamics (MD) techniques. QM/EFP-MD simulations on intra-molecular proton transfer of glycine with 290 EFP waters yielded accurate free energy change and reaction barrier of the zwitterion -> neutral form conversion. Water rearrangements turned out to be the main driving force of the proton transfer. (C) 2012 Elsevier B. V. All rights reserved.