The enhancement of photocurrents in bilayer lipid membranes by phycocyanin: pH and surface charge dependence

Effect of plastocyanin and phycocyanin on the photosensitivity of chlorophyll-containing bilayer membranes

Photovoltaic effects were studied in bilayer membranes constructed from phosphatidyl choline, monogalactosyl diglyceride, chlorophyll alpha and beta-carotene. It was demonstrated that the biliprotein C-phycocyanin enhanced the photosensitivity of these membranes. Plastocyanin, an important photosynthetic electron transfer protein, was also found to be effective in enhancing the membrane photovoltage. The C-phycocyanin and plastocyanin were effective on opposite sides of the membrane. Plastocyanin operates to transfer electrons into the membrane, while C-phycocyanin directs electron transfer from the membrane. Membranes containing monogalactosyl diglyceride were found to be extremely stable and were most susceptible to enhancement of photosensitivity by introduction of the proteins. The plastocyanin and C-phycocyanin when used together appeared to operate synergistically.