Immobilization of proteins on partially hydrolyzed agarose beads

Treatment of agarose beads with mild acid (0.2 M HCl, 55 degrees C, several hours) hydrolyzes some of the glycosidic bonds between D-galactosyl residues and 3,6-anhydro-L-galactosyl residues, and thus produces aldehydo-groups useful for immobilization of amino compounds by reductive amination with NaCNBH3. More than 20 mg (0.3 mumol) of bovine serum albumin could be coupled per gram of partially hydrolyzed agarose beads. Arthrobacter neuraminidase immobilized by this method was useful for desialylation of sialyl glycoconjugates, and was found not to leach from the gel and to be much more thermostable than the free enzyme.