CELLULOSE BEADS - A WEAK LEAKING AFFINITY SUPPORT

The release of immobilized ligands from cellulose beads was studied by solvolytic detachment of glycine, DL-leucine, azocasein and leucine aminopeptidase, which were coupled to carbonochloridate-activated supports. It is demonstrated with immobilized glycine and leucine that the urethane linkage formed between the matrix and ligands is very stable in the pH range 2-10. Comparison of the leakage with corresponding Sepharose conjugates shows the superiority of conjugates based on cellulose beads. The release of immobilized amino acids from bead cellulose was less than 1% for 1000 h at room temperature. For the immobilized proteins it is shown that the initial leakage is due to the desorption of a small amount of non-covalently bound protein (< 10%). Leakage of the proteins multi-valently bound to the matrix by the urethane bond was not detectable.