Browsing by Subject "Operational stability"

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    Immobilization of amyloglucosidase onto macroporous cryogels for continuous glucose production from starch
    (Taylor and Francis Inc., 2015) Uygun M.; Akduman B.; Ergönül B.; Aktaş Uygun D.; Akgöl S.; Denizli A.
    Poly(methyl methacrylate-glycidyl methacrylate) [Poly(MMA-GMA)] cryogels were synthesized using monomers of methylmethacrylic acid and epoxy group bearing GMA via radical cryopolymerization technique. Synthesized cryogels were used for the immobilization of amyloglucosidase to the cryogel surface using epoxy chemistry. Characterizations of the free and immobilized amyloglucosidase were carried out by comparing the optimum and kinetic parameters of enzymes. For this, pH and temperature profiles of free and immobilized preparation were studied and, it was found that, optimum pH of enzyme was not change upon immobilization (pH 5.0), while optimum temperature of the enzyme shifted 10 °C to warmer region after immobilization (optimum temperatures for free and immobilized enzyme were 55 and 65 °C, respectively). Kinetic parameters of free and immobilized enzyme were also investigated and Km values of free and immobilized amyloglucosidase were found to be 2.743 and 0.865 mg/mL, respectively. Vmax of immobilized amyloglucosidase was found to be (0.496 mol/min) about four times less than that of free enzyme (2.020 mol/min). Storage and operational stabilities of immobilized amyloglucosidase were also studied and it was showed that immobilized preparation had much more stability than free preparation. In the present work, amyloglucosidase immobilized poly(MMA-GMA) cryogels were used for continuous glucose syrup production from starch for the first time. Efficiency of immobilized enzyme was investigated and released amount of glucose was found to be 2.54 mg/mL at the end of the 5 min of hydrolysis. The results indicate that the epoxy functionalized cryogels offer a good alternative for amyloglucosidase immobilization applications with increased operational and thermal stability, and reusability. Also, these cryogels can be used for immobilization of other industrially valuable enzymes beyond amyloglucosidase. © 2015 Taylor & Francis.
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    Determination of effective assay parameters on the activity of magnetite cross-linked invertase aggregates by personal glucose meter
    (Taylor and Francis Ltd., 2022) Polatoğlu İ.; Yardım A.
    The invertase enzyme has been immobilized onto various support materials to enhance operational stability, shelf life, and reusability compared to free ones. Among the immobilization methods, carrier-free immobilization, such as cross-linked enzyme aggregates (CLEAs), attracts attention. However, recovery of the CLEAs from the reaction environment by centrifugation or filtration is a great challenge. The use of magnetic nanoparticles (Fe3O4) can overcome these separation limitations of the aggregates. For this aim, in this study, the surface of magnetite nanoparticles was functionalized with a significant number of free amino groups through silanization reaction. After precipitation of these aggregates and then cross-linking to the functionalized structure, the resulting magnetite cross-linked invertase aggregates (MCLIAs) were obtained, having different enzyme and glutaraldehyde concentrations. Magnetic nanoparticles were characterized by SEM, VSM, and FTIR analysis. The assay parameters, both constructional and experimental ones on the activity of MCLIAs, were practically determined by a personal glucose meter (PGM). The results indicate that magnetite nanoparticles with superparamagnetic behaviour were successfully functionalized with amino groups. The activity results demonstrated that experimental parameters were more effective than constructional parameters. MCLIAs also exhibited maximum activity at pH 5. Furthermore, 30-min incubation time and 35 °C were the best activity assay conditions. © 2022 Informa UK Limited, trading as Taylor & Francis Group.