Study of the thermal stability of glucose oxidase in the presence of water‐soluble polymers

Abstract

ABSTRACT:The thermal stability of glucose oxidase (GOD) in solutions containing water-soluble hydrolyzed polyacrylonitrile (HPAN) and polyoxyethylene (POE) was studied as a function of time and temperature between 28 and 60°C. The results were compared with the thermal stability of GOD in solutions without polymers. The polymers studied were found to increase the enzyme thermal stability. The influence of the concentration of the watersoluble polymers on enzyme thermal stability was also studied. The best protection effect on enzyme thermal stability had 3 wt % solution of HPAN and 1 wt % solution of polyoxyethylene. Solutions with higher concentrations led to a quick deactivation of the enzyme. It was proved that the effect of 3 wt % HPAN solution was stronger than the effect of 1 wt % POE (59.0 versus 52.0%). The thermal transition of the enzyme was studied in both the presence and the absence of HPAN by DSC. The melting temperature of GOD in the presence of HPAN was shifted to an 11°C higher value. This sustained the supposition that HPAN increases the thermostability of GOD.

Thermal Characterization of Purified Glucose Oxidase from A Newly Isolated Aspergillus Niger UAF-1

“…Gouda et al [ 36 ] reported that Aspergillus niger glucose oxidase has an activation energy of irreversible thermal denaturation is 280 kJ mol −1 , calculated from the Lumry-Eyring model. Our results are also in agreement with Godjevargova et al [ 37 ]. Table 3 is also given to indicate the comparisons between the enzyme from Aspergillus niger UAF-1 and enzyme from some other sources.…”

Immobilization of β-galactosidase on modified polypropilene membranes

“…It was found that they can be improved by adding various components to the reaction medium, such as sugars, polyoxyethylene, ethyl cellulose, polyols, amino acids, hydrophobic organic solvents and others [26][27][28][29][30][31]. The latter form multiple hydrogen bonds with amino acid residues of the enzyme to prevent it from denaturation [32].…”

One-pot HTST synthesis of responsive fluorescent ZnO@apo-enzyme composite microgels for intracellular glucometry

“…While the heat might affect the taste of the milk, HTST treatment seems to well retain the protein prole with the protein patterns of the HTST-treated milk similar to the raw milk, indicating a negligible denaturation of the proteins. 72,73 For GOx (apo-GOx), while it is usually referred to be thermally instable, biochemical changes show that it largely would not lose its biological activity and dynamic prole when subjected shortly to heat of 70 C. [80][81][82] In an additional experiment, the controlled composite microgels were obtained by continuous heating at 70.0 C under otherwise the same conditions for the synthesis of the ZnO@apo-enzyme composite microgels; standing in contrast against the ZnO@apo-enzyme composite microgels that can adapt to the uctuation in glucose concentration, the controlled composite microgels were insensitive to glucose (see Fig. S3 in ESI †).…”