Immobilization of Bacillus macerans cyclodextrin glycosyltransferase fused with poly-lysine using cation exchanger

Immobilized enzymes have provided tremendous advantages for the efficient production of biomaterials. There is increasing demand on simple and convenient protein immobilization methods because protein microarray is emerging as a cutting-edge technology for the proteome analysis and diagnosis. It has been shown that a poly-lysine tag facilitates protein purification and refolding processes. This study demonstrates that the same poly-lysine tag can be employed for the immobilization of enzyme on a solid support without deterioration of its enzymatic characteristics. Cyclodextrin glycosyltransferase (CGTase) derived from Bacillus macerans was fused to consecutive 10 lysine residues (CGTK10ase) and electrostatically immobilized on a cation exchanger. Analyses on the binding characteristics, effects of pH and temperature on enzyme stability and operational stability indicate that the poly-lysine tag is also effective for non-covalent immobilization of CGTase. Though the poly-lysine-mediated immobilization is reversible, binding force is strong enough to block protein leakage from the solid support at neutral and basic pH.