  We investigate the voltage-driven translocation of an inhomogeneously charged
polymer through a nanopore by utilizing discrete and continuous stochastic
models. As a simplified illustration of the effect of charge distribution on
translocation, we consider the translocation of a polymer with a single charged
site in the presence and absence of interactions between the charge and the
pore. We find that the position of the charge that minimizes the translocation
time in the absence of pore--polymer interactions is determined by the entropic
cost of translocation, with the optimum charge position being at the midpoint
of the chain for a rodlike polymer and close to the leading chain end for an
ideal chain. The presence of attractive or repulsive pore--charge interactions
yields a shift in the optimum charge position towards the trailing end and the
leading end of the chain, respectively. Moreover, our results show that strong
attractive or repulsive interactions between the charge and the pore lengthen
the translocation time relative to translocation through an inert pore. We
generalize our results to accommodate the presence of multiple charged sites on
the polymer. Our results provide insight into the effect of charge
inhomogeneity on protein translocation through biological membranes.
