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The isolation of photosystem-I (PS-I) from spinach has been conducted using ultrafiltration with 300 kDa molecular weight cut-off polyethersulfone membranes. The effects of ultrafiltration operating conditions on PS-I activity were optimized using parameter scanning ultrafiltration. These conditions included solution pH, ionic strength, stirring speed, and permeate flux. The effects of detergent (Triton X-100 and n-dodecyl-beta-D-maltoside) concentration on time dependent activity of PS-I were also studied using an O(2) electrode. Under optimized conditions, the PS-I purity obtained in the retentate was about 84% and the activity recovery was greater than 94% after ultrafiltration. To our knowledge, this is the first report of the isolation of a membrane protein using ultrafiltration alone.

Original publication




Journal article


Photosynth Res

Publication Date





187 - 193


Cell Membrane, Chlorophyll, Detergents, Hydrogen-Ion Concentration, Osmolar Concentration, Permeability, Photosystem I Protein Complex, Plant Proteins, Polymers, Spinacia oleracea, Sulfones, Ultrafiltration