Studies on oriented and reversible immobilization of glycoprotein using novel boronate affinity gel

The authors have previously synthesized a novel boronate affinity ligand, catechol [2-(diethylamino)carbonyl-4-bromomethyl]phenylboronate. When this ligand was coupled to cellulose beads, it bound horseradish peroxidase (HRP), a glycoprotein, at pH 7.0. In comparison, commercial m-aminophenylboronic acid-agarose did not bind HRP below pH 8.0. HRP was immobilized in an oriented and reversible fashion using this gel. The immobilized enzyme retained 90.12 per cent of its original activity, probably due to its attachment via the carbohydrate moiety of the enzyme. After repeated use, the activity remaining on the new gel was twice as high as that on conventional m-aminophenylboronic acid-agarose. The column was regenerated easily by washing with dilute acid because of reversibility of the boronate glycol bond.