  We present a theoretical investigation on possible selection of olfactory
receptors (ORs) as sensing components of nanobiosensors. Accordingly, we
generate the impedance spectra of the rat OR I7 in the native and activated
state and analyze their differences. In this way, we connect the protein
morphological transformation, caused by the sensing action, with its change of
electrical impedance. The results are compared with those obtained by studying
the best known protein of the GPCR family: bovine rhodopsin. Our investigations
indicate that a change in morphology goes with a change in impedance spectrum
mostly associated with a decrease of the static impedance up to about 60 % of
the initial value, in qualitative agreement with existing experiments on rat OR
I7. The predictiveness of the model is tested successfully for the case of
recent experiments on bacteriorhodopsin. The present results point to a
promising development of a new class of nanobiosensors based on the electrical
properties of GPCR and other sensing proteins.
