  Current voltage (I-V) characteristics in proteins can be sensitive to
conformational change induced by an external stimulus (photon, odour, etc.).
This sensitivity can be used in medical and industrial applications besides
shedding new light in the microscopic structure of biological materials. Here,
we show that a sequential tunneling model of carrier transfer between
neighbouring amino-acids in a single protein can be the basic mechanism
responsible of the electrical properties measured in a wide range of applied
potentials. We also show that such a strict correlation between the protein
structure and the electrical response can lead to a new generation of
nanobiosensors that mimic the sensorial activity of living species. To
demonstrate the potential usefulness of protein electrical properties, we
provide a microscopic interpretation of recent I-V experiments carried out in
bacteriorhodopsin at a nanoscale length.

Soft Condensed Matter;Chemical Physics