Me. Tuckerman et D. Marx, Heavy-atom skeleton quantization and proton tunneling in "intermediate-barrier" hydrogen bonds, PHYS REV L, 86(21), 2001, pp. 4946-4949
Quantum effects on proton transfer through barriers of several kcal/mol in
hydrogen bonds are investigated theoretically in malonaldehyde. Such "inter
mediate-barrier" proton transfer processes play a key role in the catalytic
activity of some enzymes. Tunneling is shown to be significant in this rea
ction even at room temperature. More importantly, the quantum nature of the
heavy molecular frame atoms is found to substantially enhance proton tunne
ling. These findings have far-reaching implications for common modeling str
ategies of proton transfer in complex systems such as biomolecules.