  By resorting to a model inspired to the standard Davydov and
Holstein-Fr\"ohlich models, in the present paper we study the motion of an
electron along a chain of heavy particles modelling a sequence of nucleotides
proper to a DNA fragment. Starting with a model Hamiltonian written in second
quantization, we use the Time Dependent Variational Principle to work out the
dynamical equations of the system. It is found that under the action of an
external source of energy transferred to the electron, and according to the
excitation site, the electron current can display either a broad frequency
spectrum or a sharply peaked frequency spectrum. This sequence-dependent charge
transfer phenomenology is suggestive of a potentially rich variety of
electrodynamic interactions of DNA molecules under the action of electron
excitation. This could imply the activation of interactions between DNA and
transcription factors, or between DNA and external electromagnetic fields.
