Proton transport along water chains and NADH hydride transfer in solution

This paper presents simulations of two biologically important processes involving proton or hydride transfer reactions. The first process is proton transport along a protonated chain of three water molecules. This process is induced with a linearly increasing external electric field. The multiconfigurational molecular dynamics with quantum transitions (MC‐MDQT) method is utilized to calculate the real‐time nonequilibrium quantum dynamics of this process. The results illustrate that nonadiabatic effects play an important role in the proton dynamics for water chains under certain nonequilibrium conditions. The second process discussed in this paper is the hydride transfer reaction from ethanol to an NAD+ analog (1‐methyl‐nicotinamide) in water with a divalent zinc ion catalyst. The structures, relative energies, and charge distributions are calculated for the reactant, product, and transition state of a complex including the NAD+ analog, ethanol, zinc, and three water molecules at the Hartree‐Fock level with a polarized valence double zeta basis set. This information is utilized to parametrize an augmented molecular mechanical potential, which is implemented to calculate the classical free energy curve for this reaction in water. The results indicate that solvation effects significantly alter the energetics of this reaction.