Voltage generation by photosystem I complexes immobilized onto a millipore filter under continuous illumination

Abstract

Here we measured the long-term photovoltage (ΔV) generation by photosynthetic pigment-protein complex of photosystem I (PS I) from cyanobacterium Synechocystis sp. PCC 6803 directly. Prior to measurements PS I was immobilized onto a Millipore membrane filter (MF) and sandwiched between two semiconductor indium tin oxide (ITO) electrodes. The ability of ITO|PS I-MF|ITO system to generate a stable ΔV over a 50 min period of irradiation by white light was detected in the presence of cytochrome c6, methyl viologen and disaccharide trehalose. Re-injection of a fresh buffer into ITO|PS I-MF|ITO preserves the immobilized PS I functionality after six months of storage at 23 °C in the dark. The developed system represents a simple bio-hybrid solar converter to obtain voltage signals under long-term, periodic illumination. This approach can also be used to couple photoactive (light-driven enzymes) and catalytic modules to generate H2 under the steady-state conditions.