Catalytic activity of bovine lactoperoxidase supported on macroporous poly(2-hydroxyethyl methacrylate-co-glycidyl methacrylate)

摘要

2-Hydroxyethyl methacrylate (HEMA) and glycidyl methacrylate (GMA) (molar ratio 85/15) are copolymerised upon γ-ray exposure at -78℃ in the presence of water to give a hydrophilic resin with a porosity that favours the anchoring of bovine-lactoperoxidase (LPO). The resin, after mincing and sieving, is obtained as irregular microparticles with size ranging from 80 to 1000 μm. The morphology of the resin in the swollen state is investigated with Inverse Steric Exclusion Chromatography and ESR. The catalytic activity of immobilised and soluble LPO is monitored and compared for 14 days at 4 ℃ as well as enzyme stability toward thermal inactivation and resistance to denaturing agents (acidity, urea, organic solvents). The results reveal a higher stability of supported LPO both in aqueous and organic media as compared with the free enzyme. Evaluation of kinetic parameters of immobilised LPO suggests that the enzyme turns out to be mainly linked to the external surface of the supporting particles.