A team of researchers from seven European research centers (SPOT-NOSED, EC project) in 2001 started working on the possibility to monitor the sensing action and, in particular, the conformational change, of some GPCRs by means of the change of their impedance spectrum.

The investigation embraced both the theoretical and the technological-experimental aspects of the problem. On the theoretical side, the influence of a conformational change on the impedance spectrum of a protein, sandwiched between ohmic contacts, has been analyzed. In order to explore this correlation, a schematic map of the protein is constructed starting from its atomic coordinates. This map is then reinterpreted as a network of elementary impedances that simulates the charge transfer through the protein contacted with an external bias, furnishing the protein impedance spectrum. The network is shape-dependent and thus the conformational change should be revealed by means of a variation of the impedance spectrum.

The research predicts, for the bovine rhodopsin, impedance variations of about 30%, in agreement with experimental measurements carried out within the electrochemical impedance spectroscopy (EIS) technique.

We believe that these results are very promising and open interesting possibilities for advances in biological knowledge and in the field of molecular electronics.