  A theory of electronic transport through molecular wires is applied to
analyze characteristics of a long-range electron transfer (ET) through
molecular bridges in macromolecules with complex donor/acceptor subsystems.
Assuming a coherent electron tunneling through the bridge to be the predominant
mechanism of ET at low temperatures it is shown that low temperature
current-voltage curves can exhibit a step-like structure, which contains
information concerning intrinsic features of ET processes such as the effect of
donor/acceptor coupling to the bridge and primary pathways of electrons
tunneling through the bridge. By contacting the proposed theoretical analysis
with such experimental data a variety of valuable characteristics of long-range
intramolecular ET can be identified. Analytical and numerical results are
presented. Using the Buttiker dephasing model within the scattering matrix
formalism we analyze dephasing effects, and we show that these effects could be
reduced enough to allow the structure of the electron transmission function to
be exposed in the experiments on the electronic transport through
macromolecules.
