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    Covalent immobilization of invertase on microporous pHEMA-GMA membrane
    (Elsevier Sci Ltd, 2004) Danisman, T; Tan, S; Kacar, Y; Ergene, A
    Poly (2-hydroxyethyl methacrylate-glycidyl methacrylate) (pHEMA-GMA) membrane was prepared by UV-initiated photopolymerization. Invertase was immobilized by the condensation reaction of the epoxy groups of glycidyl methacrylate in the membrane structure with amino groups of the enzyme. The (Km) values were 22 mM and 58 mM for free and immobilized enzyme, respectively. Immobilization improved the pH stability and temperature stability of the enzyme. Thermal stability was found to increase with immobilization. The half times for the activity decay at 70 degreesC were found to be 11 and 38 min for the free and immobilized enzyme, respectively. The immobilized enzyme activity was found to be quite stable in later experiments. (C) 2003 Elsevier Ltd. All rights reserved.
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    Entrapment of white-rot fungus Trametes versicolor in Ca-alginate beads: preparation and biosorption kinetic analysis for cadmium removal from an aqueous solution
    (Elsevier Sci Ltd, 2001) Arica, MY; Kacar, Y; Genc, O
    The biosorption of cadmium ions onto entrapped Trametes versicolor mycelia has been studied in a batch system. The maximum experimental biosorption capacities for entrapped live and dead fungal mycelia of T. versicolor were found as 102.3 +/- 3.2 mg Cd(II) g(-1) and 120.6 +/- 3.8 mg Cd(II) g(-1), respectively, Biosorption equilibrium was established in about 1 h and biosorption was well described by the Langmuir and Freundlich biosorption isotherms. The change in the biosorption capacity with time was found to fit the pseudo-second-order equation. Since the biosorption capacities were relatively high for both entrapped live and dead forms, those fungal forms could be considered as suitable biosorbents for the removal of cadmium in wastewater-treatment systems. The biosorbents were reused in three consecutive adsorption/desorption cycles without a significant loss in the biosorption capacity. (C) 2001 Elsevier Science Ltd. All rights reserved.
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    Preparation of reversibly immobilized lysozyme onto Procion Green H-E4BD-attached poly(hydroxyethylmethacrylate) film for hydrolysis of bacterial cells
    (Elsevier Sci Ltd, 2001) Kacar, Y; Arica, MY
    The flat sheet support for enzyme immobilization was prepared by UV-initiated photopolymerization of 2-hydroxyethyl-methacrylate (HEMA) in the presence of an initiator (alpha alpha'-azoisobutyronitrile. AIBN). An affinity dye, Procion Green H-E4BD, was attached covalently under alkaline conditions and the pHEMA-Procion Green H-E4BD-attached film was used for the immobilization of lysozyme via adsorption. The amount of attached dye on the pHEMA film was 160 mu mol m(2) and the water content of the dye-attached pHEMA film was 69%. The lysozyme adsorption capacity of the dye-attached pHEMA film was determined under conditions of different pH and with different initial concentrations of enzyme in the medium. The maximum lysozyme adsorption capacity of the dye-attached pHEMA film, under the specified experimental conditions was 3.92 g m(-2). Non-specific adsorption of the lyzozyme on the pHEMA film was negligible, Optimum reaction pH was 6.0 for the free and 7.0 for adsorbed enzyme. The free enzyme had an optimum temperature of 35 degreesC. whereas it shifted to 40 degreesC for the immobilized enzyme system. The enzyme could be repeatedly adsorbed and desorbed from the dye-attached pHEMA film without any significant loss in adsorption capacity. (C) 2001 Elsevier Science Ltd. All rights reserved.
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    Procion Green H-E4BD-immobilized porous poly(hydroxyethylmethacrylate) ion-exchange membrane: preparation and application to lysozyme adsorption
    (Elsevier Science Bv, 2001) Kacar, Y; Arica, MY
    Lysozyme adsorption onto Procion Green HE-4BD-immobilized poly(2-hydroxyethylmethacrylate) (pHEMA) membrane were investigated. The membrane were prepared by ultraviolet-initiated photopolymerization of HEMA in the presence of an initiator (alpha-alpha'-azoisobutyronitrile; AIBN). The water content of the dye-immobilized membrane was 69%, the amount of immobilized dye on the membrane was 0.544 mu mol ml(-1) and it used in the lysozyme adsorption studies. Lysozyme adsorption on these membranes from aqueous solutions containing different amounts of lysozyme at different pH was investigated in batch reactors. Lysozyme adsorption capacity of the dye-immobilized membrane was 13.33 mg ml(-1). The maximum lysozyme adsorption capacity (q(m)) of the dye-immobilized wet membrane was 14.14 mg ml(-1) and the dissociation constant (kd) value was found to be 0.707 mg ml(-1) lysozyme. More than 95% of the adsorbed lysozyme were desorbed in 120 min in the desorption medium containing 0.5 M KCl at pH 6.0. (C) 2001 Elsevier Science B.V. All rights reserved.