Characteristics and the Mechanism of Bacteriorhodopsin Photoelectric Response

Oriented bacteriorhodopsin films were prepared on ITO conductive glass by using electrophoretic or Langmuir-Blodgett methods to construct photocells. Pulse response photovoltages under stimulation of pulsed laser and differentialresponse signals under irradiation of discontinued light were respectively measured, and the origins of the two responses and their correlation are analyzed. The pulse response photovoltage initiated from the ultrafast charge separation of the retinal and the proton translocation, followed by the deprotonation and reprotonation of the Schiff base and its surrounding amino acids. This was a quick response and was the preceding reaction of the differential response. The differential response was caused by the charging and discharging of the continuous proton current of the BR light-driven proton pump at the light-on and light-off, as well as the coupling mode of the measuring circuit, which was a slow process.