Yazar "Muderrisoglu C." seçeneğine göre listele
Listeleniyor 1 - 5 / 5
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Application of ?-glucuronidase-immobilised silica gel formulation to microfluidic platform for biotransformation of ?-glucuronides(Springer Netherlands, 2018) Muderrisoglu C.; Sargin S.; Yesil-Celiktas O.Objective: To improve the efficiency of reactions of ?-glucuronidase (GUS)-assisted glucuronic acid (GluA) removal within a microfluidic system. Results: ?-glucuronidase from Helix pomatia was immobilised and characterised in silica-based sol–gel monoliths. Efficiency of the GUS-doped silica monoliths was tested for hydrolysis of p-Nitrophenyl-?-d-glucuronide (pNP–GluA) in both ml-scaled medium via batch reactions and microfluidic environment via continuous-flow reactions. In the microfluidic platform, within a duration of 150 min of continuous operation (flow rate: 1 µL/min), the obtained highest pNP yield was almost 50% higher than that of the corresponding batchwise reaction. However, increased flow rates (3, 5, and 10 µL/min) resulted in lower conversion yields compared to 1 µL/min. The microfluidic platform demonstrated continuous hydrolytic activity for 7 days with considerable reaction yields while using a small amount of the enzyme. Conclusion: These results revealed that usage of the microreactors has considerable potential to efficiently obtain bioactive GluA-free aglycons from various plant-derived ?-glucuronides for pharmaceutical applications. © 2018, Springer Science+Business Media B.V., part of Springer Nature.Öğe Application of ß-glucuronidase-immobilised silica gel formulation to microfluidic platform for biotransformation of ß-glucuronides(Springer Netherlands, 2018) Muderrisoglu C.; Sargin S.; Yesil-Celiktas O.Objective: To improve the efficiency of reactions of ß-glucuronidase (GUS)-assisted glucuronic acid (GluA) removal within a microfluidic system. Results: ß-glucuronidase from Helix pomatia was immobilised and characterised in silica-based sol–gel monoliths. Efficiency of the GUS-doped silica monoliths was tested for hydrolysis of p-Nitrophenyl-ß-d-glucuronide (pNP–GluA) in both ml-scaled medium via batch reactions and microfluidic environment via continuous-flow reactions. In the microfluidic platform, within a duration of 150 min of continuous operation (flow rate: 1 µL/min), the obtained highest pNP yield was almost 50% higher than that of the corresponding batchwise reaction. However, increased flow rates (3, 5, and 10 µL/min) resulted in lower conversion yields compared to 1 µL/min. The microfluidic platform demonstrated continuous hydrolytic activity for 7 days with considerable reaction yields while using a small amount of the enzyme. Conclusion: These results revealed that usage of the microreactors has considerable potential to efficiently obtain bioactive GluA-free aglycons from various plant-derived ß-glucuronides for pharmaceutical applications. © 2018, Springer Science+Business Media B.V., part of Springer Nature.Öğe Formulation of organic and inorganic hydrogel matrices for immobilization of ß-glucosidase in microfluidic platform(Wiley-VCH Verlag, 2017) Kazan A.; Heymuth M.; Karabulut D.; Akay S.; Yildiz-Ozturk E.; Onbas R.; Muderrisoglu C.; Sargin S.; Heils R.; Smirnova I.; Yesil-Celiktas O.The aim of this study was to formulate silica and alginate hydrogels for immobilization of ß-glucosidase. For this purpose, enzyme kinetics in hydrogels were determined, activity of immobilized enzymes was compared with that of free enzyme, and structures of silica and alginate hydrogels were characterized in terms of surface area and pore size. The addition of polyethylene oxide improved the mechanical strength of the silica gels and 68% of the initial activity of the enzyme was preserved after immobilizing into tetraethyl orthosilicate–polyethylene oxide matrix where the relative activity in alginate beads was 87%. The immobilized ß-glucosidase was loaded into glass–silicon–glass microreactors and catalysis of 4-nitrophenyl ß-d-glucopyranoside was carried out at various retention times (5, 10, and 15 min) to compare the performance of silica and alginate hydrogels as immobilization matrices. The results indicated that alginate hydrogels exhibited slightly better properties than silica, which can be utilized for biocatalysis in microfluidic platforms. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, WeinheimÖğe High-Yield Biocatalysis of Baicalein 7-O-ß-d-Glucuronide to Baicalein Using Soluble Helix pomatia-Derived ß-Glucuronidase in a Chemically Defined Acidic Medium(Springer New York LLC, 2019) Muderrisoglu C.; Yesil-Celiktas O.Abstract: Baicalein, showing stronger pharmacological activity, can be obtained by removal of the distal glucuronic acid (GluA) from baicalein 7-O-ß-D-glucuronide (baicalin). In the present study, a chemically defined reaction medium comprised of mildly acidic (pH 4.5, 37 °C) aqueous solution, was formulated for biotransformation of baicalin to baicalein using acidic Helix pomatia derived beta-glucuronidase (HP-GUS), an untested biocatalyst source. The biotransformation was carried out as a batchwise process within an optimised reaction cocktail (with 5% dimethylformamide, v/v) by a 4-h HP-GUS (250 unit/ml) incubation of baicalin (60 ppm) and resulted in a promising conversion ratio of 99% without any by-product formation. The formulated reaction system may offer a novel and efficient alternative for bioproduction of baicalein, which can be vital for pharmaceutical applications. Graphical Abstract: [Figure not available: see fulltext.]. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.Öğe Modelling coupled dynamics of diffusive–convective mass transfer in a microfluidic device and determination of hydrodynamic dispersion coefficient(Taiwan Institute of Chemical Engineers, 2017) Yildiz-Ozturk E.; Yucel M.; Muderrisoglu C.; Sargin S.; Yesil-Celiktas O.One of the challenges in mathematical modelling of microchips is the lack of available data for dispersion coefficients of biomolecules. The main focus of this study was to determine the hydrodnamic dispersion coefficients of the model substrates, 4-Nitrophenyl-ß-D-glucopyranoside (pNPG_1) and 4-Nitrophenyl-ß-D-glucuronide (pNPG_2) for ß-glucosidase and ß-glucoronidase. The substrate solutions were pumped through the silica porous gel inside the S-shaped PDMS microreactor at flow rates of 1, 3 and 5 µl/min. The output flow was collected with respect to time and quantified by UPLC. The general mathematical model was derived for the coupled dynamics of convective–diffusive mass transfer and a computational algorithm was developed for the numerical solutions of the derived partial differential equations in MATLAB. The hydrodynamic dispersion coefficients of pNPG_1 were determined as 0.370 × 10-6, 3.638 × 10-6 and 11.680 × 10-6 m2/s, while as 0.368 × 10-6, 1.515 × 10-6and 3.503 × 10-6m2/s for pNPG_2 at respective flow rates. Furthermore, the relations between dispersion coefficients and flow rates were investigated. Obtained hydrodynamic dispersion coefficients can be used for modelling of pNPG reactions which may also be adapted to other enzyme related reactions within life sciences. © 2017 Taiwan Institute of Chemical Engineers
