Decrease in yeast glucose-6-phosphate dehydrogenase activity due to oxygen free radicals

Dumitru, Ioan; Nechifor, Marina Tamara

doi:10.1016/0020-711x(94)90150-3

Cited by 7 publications

(3 citation statements)

References 16 publications

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“…Reduction of the activity in presence of only LAP is observed because the initiator radicals can also be generated under daylight. The inactivation of enzymes by free radicals has been reported before ( Dumitru and Nechifor, 1994 ). The unchanged activity of the samples exposed to only UV shows that the inactivation is not caused by irradiation and/or heat generated from the UV-LEDs.…”

Section: Resultsmentioning

confidence: 78%

Immobilization of β-Galactosidase by Encapsulation of Enzyme-Conjugated Polymer Nanoparticles Inside Hydrogel Microparticles

Suvarli

Wenger

Serra

et al. 2022

Front. Bioeng. Biotechnol.

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Increasing the shelf life of enzymes and making them reusable is a prominent topic in biotechnology. The encapsulation inside hydrogel microparticles (HMPs) can enhance the enzyme’s stability by preserving its native conformation and facilitating continuous biocatalytic processes and enzyme recovery. In this study, we present a method to immobilize β-galactosidase by, first, conjugating the enzyme onto the surface of polymer nanoparticles, and then encapsulating these enzyme-conjugated nanoparticles (ENPs) inside HMPs using microfluidic device paired with UV-LEDs. Polymer nanoparticles act as anchors for enzyme molecules, potentially preventing their leaching through the hydrogel network especially during swelling. The affinity binding (through streptavidin-biotin interaction) was used as an immobilization technique of β-galactosidase on the surface of polymer nanoparticles. The hydrogel microparticles of roughly 400 μm in size (swollen state) containing unbound enzyme and ENPs were produced. The effects of encapsulation and storage in different conditions were evaluated. It was discovered that the encapsulation in acrylamide (AcAm) microparticles caused an almost complete loss of enzymatic activity. Encapsulation in poly(ethylene glycol) (PEG)-diacrylate microparticles, on the other hand, showed a residual activity of 15–25%, presumably due to a protective effect of PEG during polymerization. One of the major factors that affected the enzyme activity was presence of photoinitiator exposed to UV-irradiation. Storage studies were carried out at room temperature, in the fridge and in the freezer throughout 1, 7 and 28 days. The polymer nanoparticles showcased excellent immobilization properties and preserved the activity of the conjugated enzyme at room temperature (115% residual activity after 28 days), while a slight decrease was observed for the unbound enzyme (94% after 28 days). Similar trends were observed for encapsulated ENPs and unbound enzyme. Nevertheless, storage at −26°C resulted in an almost complete loss of enzymatic activity for all samples.

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Section: Resultsmentioning

confidence: 78%

Immobilization of β-Galactosidase by Encapsulation of Enzyme-Conjugated Polymer Nanoparticles Inside Hydrogel Microparticles

Suvarli

Wenger

Serra

et al. 2022

Front. Bioeng. Biotechnol.

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“…It is possible that this decline corresponds to an accumulation of free radicals produced as the fermentation continues. It has been suggested previously (19) that enzyme activity in Saccharomyces cerevisiae decreases with increasing free radical concentrations. However, free radical levels were not determined during these experiments.…”

Section: Discussionmentioning

confidence: 85%

Life Cycle Cost Analysis as Decision Support Tool in Chemical Process Development

2014

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Today, it is common sense that environmentally benign chemical production processes are needed as the basis for future competitiveness and long‐term sustainability. Decision support in the development of such processes can be provided by life cycle assessment. New technologies, however, can be established only if they lead to cost‐efficient production processes as well. Life cycle costing analyses provide an appropriate methodological basis linking the cost‐side evaluation of alternative options during the process development with environmental decision criteria. The results of both methods can be combined in an eco‐portfolio. In summary, development of both ecologically and economically efficient processes can thus already be supported in the early design phase of the chemical processes.

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“…Besides mass transfer limitations, stress-induced enzyme inactivation and leaching during the wash steps may cause a reduced apparent activity. Potential sources of stress-induced enzyme inactivation in the applied process are the contact with highly hydrophobic organic compounds in the organic phase (Iyer and Ananthanarayan, 2008 ) or monomer species in the aqueous phase, high shear forces during the emulsification process (Bekard et al, 2011 ) or UV irradiation (Luse and McLaren, 1963 ; Vladimirov et al, 1970 ), free radicals (Dumitru and Nechifor, 1994 ) and increased temperature (Ustok et al, 2010 ) during the exothermic photo-crosslinking reaction. The measured activities alone cannot give any indication about the predominant aspect leading to reduced apparent activity.…”

Section: Discussionmentioning

confidence: 99%

3D-Printable and Enzymatically Active Composite Materials Based on Hydrogel-Filled High Internal Phase Emulsions

Wenger

Radtke

Göpper

et al. 2020

Front. Bioeng. Biotechnol.

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The immobilization of enzymes in biocatalytic flow reactors is a common strategy to increase enzyme reusability and improve biocatalytic performance. Extrusion-based 3D bioprinting has recently emerged as a versatile tool for the fabrication of perfusable hydrogel grids containing entrapped enzymes for the use in such reactors. This study demonstrates the suitability of water-in-oil high internal phase emulsions (HIPEs) as 3D-printable bioinks for the fabrication of composite materials with a porous polymeric scaffold (polyHIPE) filled with enzyme-laden hydrogel. The prepared HIPEs exhibited excellent printability and are shown to be suitable for the printing of complex three-dimensional structures without the need for sacrificial support material. An automated activity assay method for the systematic screening of different material compositions in small-scale batch experiments is presented. The monomer mass fraction in the aqueous phase and the thickness of printed objects were found to be the most important parameters determining the apparent activity of the immobilized enzyme. Mass transfer limitations and enzyme inactivation were identified as probable factors reducing the apparent activity. The presented HIPE-based bioinks enable the fabrication of flow-optimized and more efficient biocatalytic reactors while the automated activity assay method allows the rapid screening of materials to optimize the biocatalytic efficiency further without time-consuming flow-through experiments involving whole printed reactors.

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Decrease in yeast glucose-6-phosphate dehydrogenase activity due to oxygen free radicals

Cited by 7 publications

References 16 publications

Immobilization of β-Galactosidase by Encapsulation of Enzyme-Conjugated Polymer Nanoparticles Inside Hydrogel Microparticles

Immobilization of β-Galactosidase by Encapsulation of Enzyme-Conjugated Polymer Nanoparticles Inside Hydrogel Microparticles

Life Cycle Cost Analysis as Decision Support Tool in Chemical Process Development

3D-Printable and Enzymatically Active Composite Materials Based on Hydrogel-Filled High Internal Phase Emulsions

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