Improved stabilization of genetically modified penicillin G acylase in the presence of organic cosolvents by co-immobilization of the enzyme with polyethyleneimine

Penicillin G acylase (PGA) is an enzyme that hardly interacts with polycationic polymers (e.g., polyethyleneimine, PEI) and thus the enzyme cannot be stabilized against the action of organic solvents by its co-immobilization with the polymer in the same support, neither covalently attached to the support nor adsorbed on the already immobilized enzyme. However, a new mutant PGA bearing eight additional Glu residues homogenously distributed throughout the enzyme surface may interact with the polymer. The co-immobilization of the enzyme and PEI on glyoxyl-agarose allows one to fully take advantage of the stabilization produced by the multipoint covalent attachment and by the protective hydrophilic micro-environment generated by the polycationic polymer, enabling a significant stabilization of the immobilized PGA in the presence of organic solvents.