Vinyl triazole carrying metal-chelated beads for the reversible immobilization of glucoamylase
Date
2011-06-05
Authors
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Journal ISSN
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Publisher
Wiley
Abstract
Poly(ethylene glycol dimethacrylate-1-vinyl-1,2,4-triazole) [poly(EGDMA-VTAZ)] beads with an average diameter of 100-200 μm were obtained by the copolymerization of ethylene glycol dimethacrylate (EGDMA) with 1-vinyl-1,2,4-triazole (VTAZ). The copolymer hydrogel bead composition was determined by elemental analysis and was found to contain 5 EGDMA monomer units for each VTAZ monomer unit. The poly(EGDMA-VTAZ) beads were characterized by swelling studies and scanning electron microscopy (SEM). The specific surface area of the poly(EGDMA-VTAZ) beads was found 65.8 m2/g. Cu 2+ ions were chelated on the poly(EGDMA-VTAZ) beads. The Cu 2+ loading was 82.6 μmol/g of support. Cu2+-chelated poly(EGDMA-VTAZ) beads with a swelling ratio of 84% were used in the immobilization of Aspergillus niger glucoamylase in a batch system. The maximum glucoamylase adsorption capacity of the poly(EGDMA-VTAZ)-Cu2+ beads was 104 mg/g at pH 6.5. The adsorption isotherm of the poly(EGDMA-VTAZ)-Cu 2+ beads fitted well with the Langmuir model. Adsorption kinetics data were tested with pseudo-first- and second-order models. The kinetic studies showed that the adsorption followed a pseudo-second-order reaction model. The Michaelis constant value for the immobilized glucoamylase (1.15 mg/mL) was higher than that for free glucoamylase (1.00 mg/mL). The maximum initial rate of the reaction values were 42.9 U/mg for the free enzyme and 33.3 U/mg for the immobilized enzyme. The optimum temperature for the immobilized preparation of poly(EGDMA-VTAZ)-Cu2+-glucoamylase was 65°C; this was 5°C higher than that of the free enzyme at 60°C. The glucoamylase adsorption capacity and adsorbed enzyme activity slightly decreased after 10 batch successive reactions; this demonstrated the usefulness of the enzyme-loaded beads in biocatalytic applications. The storage stability was found to increase with immobilization.
Description
Keywords
Polymer science, Adsorption, Eenzymes, Metal-polymer complexes, Afiinity chromatography, Catalase, Adsorption, Purification, Adsorption, Catalysts, Chelation, Chemical analysis, Copolymerization, Copolymers, Enzyme activity, Enzyme immobilization, Ethylene, Ethylene glycol, Monomers, Nitrogen compounds, Scanning electron microscopy, Adsorbed enzyme, Adsorption capacities, Adsorption kinetics, Aspergillus niger, Average diameter, Batch systems, Biocatalytic applications, Copolymer hydrogels, Elemental analysis, Ethylene glycol dimethacrylate, Free enzyme, Glucoamylase, Immobilized enzyme, Initial rate, Kinetic study, Langmuir models, Metal-polymer complexes, Michaelis constants, Monomer units, Optimum temperature, Reversible immobilization, Second-order models, Second-order reaction, SEM, Storage stability, Swelling ratio, Swelling studies, Enzymes
Citation
Kök, S. vd. (2011). "Vinyl triazole carrying metal-chelated beads for the reversible immobilization of glucoamylase". Journal of Applied Polymer Science, 120(5), 2563-2570.