Compact parameter set for fast estimation of proton transfer rates

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.