Properties of Protein Adsorption and Desorption of Alumina Ceramic Membrane

Abstract

The properties of protein adsorption and desorption of alumina ceramic membranes were investigated using several types of proteins. The effect of pH on the protein adsorption was studied by soaking the membrane in protein solution. For basic proteins, the amount of protein adsorbed increased at pHS Iower than the isoelectric point due to an electrostatic interaction between the protein and the membrane. A single protein solution was filtered and the protein was adsorbed on the membrane. Most of the adsorbed protein was desorbed and conceutrated by changing the ionic strength or pH of the filtered solvent, however, the protein remaining on the membrane was not washed out even by soaking in sodium lauryl sulfate (SDS) solution. The adsorption-desorption experiments were carried out using a binary protein solution of lysozyme and p-galactosidase of pH 3 for the adsorption step and phosphate buffer solution of pH 7 for the desorption step. During the adsorption step, P-galactosidase was adsorbed more than the lysozyme, however, the absolute adsorbed amount was smaller than that in the single protein solution of P-galactosidase since the adsorption site was partially occupied by lysozyme. P-Galactosidase was concentrated seven-fold in the permeate during the desorption step in the first 20 s, while the concentration of lysozyme was one-tenth of its original value.