Detecting conformational change by current transport in proteins: The case of bacteriorhodopsin monolayers

Recent experiments on the light receptor bacteriorhodopsin have revealed the protein conductive properties and connected them to its sensing action. In particular it was shown that the super-Ohmic I-V characteristic acquired in dark, changes in the presence of green light, with an enhancement of current at increasing bias values. Here we propose a current transport model for proteins able to reproduce experimental data, mainly the dependence of current on their three dimensional (tertiary) structure. The model is based on a resistance network model and implements a tunneling mechanism of charge transfer between the amino-acids constituting the protein.