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    Öğe
    Acrylamide-Sepiolite Based Composite Hydrogels for Immobilization of Invertase
    (Wiley, 2009) Oztop, H. Nursevin; Hepokur, Ceylan; Saraydin, Dursun
    Novel composite hydrogels, poly(acrylamide)-sepiolite (PAS), poly(acrylamide/acrylic acid)-sepiolite (PAAS), and poly(acrylamide/itaconic acid)-sepiolite (PAIS) were prepared and used for the immobilization of invertase. The parameters of equilibrium swelling, diffusional exponent, and diffusion coefficient of these hydrogels were calculated from swelling experiments. Invertase was immobilized onto PAS, PAAS, and PAIS and immobilized invertases (PASI, PAASI, and PAISI) were prepared. Optimum pH values for free invertase, PASI, PAASI, and PAISI are found to be 5, 5.5, 4.5, and 6, respectively, and the optimum temperatures were 30, 50, 50, and 35 degrees C for free invertase PASI, PAASI, and PAISI. It was found that K-m values of free invertase, PASI, PAASI, and PAISI were 11.3, 41.0, 94.5, and 56.0 mM, respectively. V-max values were 2 mu mol/min for free invertase, 8.10 mu mol/min for PASI, 1.30 mu mol/min for PAASI, and 0.42 mu mol/min for PAISI, respectively. The invertase immobilized hydrogels showed excellent, temperature, storage, and operational stability.
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    Öğe
    Poly(acrylamide/maleic acid)-sepiolite composite hydrogels for immobilization of invertase
    (Springer, 2010) Oztop, H. Nursevin; Hepokur, Ceylan; Saraydin, Dursun
    Poly(acrylamide/maleic acid) and sepiolite (PAMS) composite hydrogel was prepared and used for the immobilization of invertase. In FTIR analysis, the characteristic bands of composite such as -OH, -COOH, Si-OH show the evidence of sepiolite and maleic acid. In TGA analysis, water loss, decomposition of amide side groups and breakdown of main chain regions of the composite were found. The parameters of equilibrium swelling, initial swelling rate, diffusional exponent, and diffusion coefficient were calculated and evaluated from swelling experiments in distilled water. Invertase was immobilized onto PAMS by adsorption and poly(acrylamide/maleic acid)-sepiolite-invertase (PAMSI) was prepared. Optimum pH, optimum temperature values for free invertase and PAMSI were found. It was found that K (m) values of free invertase and PAMSI were 11.3 and 34.1 mM, respectively. V (max) value was found that 2.0 mu mol min(-1) for free invertase and 13.9 mu mol min(-1) for PAMSI, respectively. PAMSI showed excellent temperature, operational and storage stability.