MOLECULAR-INTERACTIONS BETWEEN PROTEINS AND SYNTHETIC MEMBRANE POLYMER-FILMS

To help understand the effects of protein adsorption on membrane filtr ation performance, we have measured the molecular interactions between cellulose acetate films and two proteins with different properties (r ibonuclease A and human serum albumin) with a surface force apparatus. Comparison of forces between two protein layers with those between a protein layer and a cellulose acetate (CA) film shows that, at high pH , both proteins retained their native conformation on interacting with the CA film while at the isoelectric point (pI) or below the tertiary structure of proteins was disturbed. These measurements provide the f irst molecular evidence that disruption of protein tertiary structure could be responsible for the reduced permeation flows observed during membrane filtration of protein solutions and suggest that operating at high pH values away from the pI of proteins will reduce such fouling.