Several proton transfer systems were studied by quantum chemical calculatio
ns in the presence of further ligand waters. The calculated proton transfer
barriers are fitted by an analytical expression, which allows for fast cal
culation of proton transfer rates between common donor-acceptor pairs in bi
ological systems under the influence of surrounding chemical groups. The on
ly information required is the chemical nature of the donor and acceptor, t
he distance between donor and acceptor, and the environmental influence in
the acceptor and donor bound states. The quantum nature of the transferred
proton is approximated at the level of an effective zero-point energy along
the reaction coordinate. The approach presented allows efficient calculati
on of transfer rates and allows to include proton hopping events between ti
tratable sites in classical molecular dynamics simulations. (C) 2001 Americ
an Institute of Physics.