Monitoring the Charge Distribution during Proton and Sodium Ion Conduction along Chains of Water Molecules and Protein Residues

Abstract

AbstractQuantum calculations are used to determine the level of delocalization of the charge of a cation as it translates along a chain of water molecules or glycine residues. Charge dispersal is monitored via the molecular electrostatic potential and the dipole moment of the entire system. The positive charge is largely localized on the water molecule on which the proton is situated, but becomes more intense and extended as the proton moves along the chain. The positive charge is more delocalized in protonated polyglycine, where it extends over at least an entire residue. Displacement of the proton along the chain intensifies the charge, and progressively polarizes the entire chain. This pattern of charge intensification is more profound in both the 310 and α‐helical structures. An Na+ cation behaves in much the same way as H+ in terms of charge migration.