Topological characterization and immobilization of a chromatophore membrane from Rhodopseudomonas viridis for application as a photoelectrical device

Abstract

We characterized topological orientation of bacterial photosynthetic membranes (chromatophores) from Rhodopseudomonas viridis using antibodies against H- and C-subunit of photosynthetic reaction center protein (RC). About 40% of the membranes were unsealed vesicles in the inside-out orientation exposing the cytoplasmic side whereas 20% of those were unsealed vesicles in the right side-out orientation expo-sing the periplasmic side. The residual 20% was in the form of a flat sheet structure. We immobilized the chromatophore membranes onto an indium–tin-oxide (ITO) electrode by the electro-deposition method. The electro-deposited film (ED film) showed photocurrent and photovoltage between different electrodes such as ITO and gold (Au). Addition of buffer salts such as sodium phosphate enhanced very much the photoelectrical response in the ED film.