Use of Ion Exchange Membranes for Selective Recovery of Aspergillus awamori Glucoamylase and Phage T4 Lysozyme

Our research examined whether enhanced separation and purification of mutant enzymes could be obtained on ion-exchange membranes. Solutions of three mutants of Aspergillus awamori glucoamylase were passed through an anionic exchange membrane, as well as one mutant of T4 lysozyme through a cationic exchange membrane. The mutant enzymes were modified by adding charged fusions\u27\u27, polypeptides of either aspartic acid residues to increase the overall negative charge of the enzyme or arginine residues to increase the overall positive charge. The effect of the mutations on the purification of glucoamylase from a modified fermentation broth were examined at two different elution pHs, 4.5 and 6.0. The use of the charged fusions provided significantly improved purification capabilities over control versions. Both the small scale glucoamylase runs and the scaled up experiments had overall purification factors of around two, with a peak purification factor of near 7 for GA\u27CDlO. Elution of glucoamylase at pH 4.5 did not lead to an increase in separability as compared to that obtained at pH 6.0. Initial trials using a purified lysozyme mutant showed significant binding capabilities. Further experiments with this protein need to be done to determine scale up potential