title: Improved covalent immobilization of horseradish peroxidase on macroporous glycidyl methacrylate-based copolymers.
abstract: A macroporous copolymer of glycidyl methacrylate and ethylene glycol dimethacrylate, poly(GMA-co-EGDMA), with various surface characteristics and mean pore size diameters ranging from 44 to 200 nm was synthesized, modified with 1,2-diaminoethane, and tested as a carrier for immobilization of horseradish peroxidase (HRP) by two covalent methods, glutaraldehyde and periodate. The highest specific activity of around 35 U g(-1) dry weight of carrier was achieved on poly(GMA-co-EGDMA) copolymers with mean pore diameters of 200 and 120 nm by the periodate method. A study of deactivation kinetics at 65 °C and in 80 % dioxane revealed that periodate immobilization also produced an appreciable stabilization of the biocatalyst, while stabilization factor depended strongly on the surface characteristics of the copolymers. HRP immobilized on copolymer with a mean pore diameter of 120 nm by periodate method showing not only the highest specific activity but also good stability was further characterized. It appeared that the immobilization resulted in the stabilization of enzyme over a broader pH range while the Michaelis constant value (K                 (m)) of the immobilized HRP was 10.8 mM, approximately 5.6 times higher than that of the free enzyme. After 6 cycles of repeated use in a batch reactor for pyrogallol oxidation, the immobilized HRP retained 45 % of its original activity.
authors.affiliation: Institute for Multidisciplinary Research, University of Belgrade, Kneza Višeslava 1, Belgrade, Serbia.
authors.forename: Olivera
authors.initials: O
authors.lastname: Prodanović
authors.forename: Miloš
authors.initials: M
authors.lastname: Prokopijević
authors.forename: Dragica
authors.initials: D
authors.lastname: Spasojević
authors.forename: Zeljko
authors.initials: Z
authors.lastname: Stojanović
authors.forename: Ksenija
authors.initials: K
authors.lastname: Radotić
authors.forename: Zorica D
authors.initials: ZD
authors.lastname: Knežević-Jugović
authors.forename: Radivoje
authors.initials: R
authors.lastname: Prodanović
mesh_terms: D004800:Enzymes, Immobilized / Q000737:chemistry*; D004852:Epoxy Compounds / Q000737:chemistry; D005026:Ethylene Glycols; D005976:Glutaral / Q000737:chemistry; D006735:Horseradish Peroxidase / Q000737:chemistry*; D006860:Hydrogen Bonding; D007700:Kinetics; D008689:Methacrylates / Q000737:chemistry*; D010504:Periodic Acid / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D011748:Pyrogallol / Q000737:chemistry; D013499:Surface Properties
chemical_list: D004800:Enzymes, Immobilized; D004852:Epoxy Compounds; D005026:Ethylene Glycols; D008689:Methacrylates; D011108:Polymers; C526534:poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate); D011748:Pyrogallol; D010504:Periodic Acid; C009288:metaperiodate; D006735:Horseradish Peroxidase; C007870:glycidyl methacrylate; D005976:Glutaral