Glucose Oxidase Activity

Fig. 19 Rapid lifetime determination imaging of the activity of glucose oxidase. Gray-scale image of the activity of glucose oxidase (left) and resulting calibration curve (right). Experiments were performed in triplicate (rows). The wells in the images contained, from 1 to 12, glucose oxidase activities of 0 (blank), 135, 54.1, 27.1, 13.5, 5.4, 2.7, 1.35, 0.54, 0.27, 0.14, and 0.05 mU ml. 1 respectively, 100 jiL of a 0.2 mmol L-1 EuTc solution, and 15 jiL of a 277.2 mmol I. 1 glucose solution. The total volume was made up to 200 xL with MOPS buffer...

Application and Principle This procedure is used to determine glucose oxidase activity in preparations derived from Aspergillus niger var. The assay is based on the titrimetric measurement of gluconic acid produced in the presence of excess substrate and excess air. 

Amyloglucosidase Activity), 798 Glucose Isomerase Activity, 796 Glucose Oxidase Activity, 798 P-D-Glucosidase Activity, 798 Hemicellulase Activity, 799 Invertase Activity, 800 Lactase (Acid) (P-Galactosidase) Activity, 802... 

Prosthetic group Enzyme FAD Glucose-6-phosphate dehydrogenase Glucose oxidase activity... 

Kost, J., et al, Glucose sensitive membranes containing glucose oxidase activity, swelling, and permeability studies. Journal of Biomedical Materials Research, 1984, 19, 1117-1133. 

In commercial large scale catalytic conversions, activity maintenance is important. Calculations by Chang Indicating the glucose oxidase activity profiles vs. distance In the catalyst pellet are shown In Figure 7 for various catalase enzyme loadings... 

Figure 20.1 The pH dependence of glucose oxidase activity for soluble (O) and immobilized ( ) forms (Cho and Bailey, 1978)...

It has been shown (Ollis, 1972 Karanth and Bailey, 1978 Reilly and Lee, 1981) that the effect of slow diffusion in general is to increase the width of the pH versus apparent stability curve. This is illustrated in Figure 20.1 for glucose oxidase activity (Cho and Bailey, 1978). 

A variation of the EMIT is the apoenzyme reconstruction immunoassay system, where the analyte is coupled not to the enzyme itself but to a cofactor or prosthetic group that is required for enzyme activity. For example, the analyte may be coupled to flavin-adenine dinucleotide (FAD), which is required for glucose oxidase activity. The antibody binds to the FAD-analyte conjugate and prevents FAD from interacting with the enzyme, whose activity is consequently reduced. The more analyte present in the sample, the more competition there is for the antibody and the more FAD-analyte conjugate remains free in solution and available to the enzyme. Again, the level of enzyme activity is related to the quantity of analyte in the sample. 

Glucose oxidase presence in honey is also derived from bees. Its optimum pH is 6.1. The enzyme oxidizes glucose (100%) and mannose (9%). The enzymatic oxidation by-product, hydrogen peroxide, is partly responsible for a bacteriostatic effect of nonheated honey, an effect earlier ascribed to a so-called inhibine . The enzymatic oxidation yields gluconic acid, the main acid in honey. Glucose oxidase activity and thermal stability in honey vary widely (limit values were given in Ta-... 

The principal organic acid in honey is gluconic acid, which results from glucose oxidase activity. 

In honey gluconic acid is in equilibrium with its gluconolactone. The acid level is mostly dependent on the time elapsed between nectar collection by bees and achievement of the final honey density in honeycomb cells. Glucose oxidase activity drops to a negligible level in thickened honey. Other acids present in honey only in small amounts are acetic, butyric, lactic, citric, succinic, formic, maleic, malic and oxalic acids. 

Removal of glucose has been used successfully in the production of powdered (dried) whole eggs and egg whites. Glucose is oxidised to inactive gluconic acid by the addition of a yeast preparation with glucose oxidase activity, or by the addition of glucose oxidase enzyme. Simultaneous removal of oxygen slows down the autoxidation reaction. 

I. Dupont, D. Feron, and G Novel, Effect of glucose oxidase activity on corrosion potenital of stainless steels in seawater, Int. Biodeterioration Biodegradation 47 13-18 (1998). 

In order to model the behavior of the reactor, the enzyme activities and the mutarotation rate constants had to be separately determined. The invertase activity was determined by measurements similar to those described above the glucose oxidase activity was determined in the... 

What one can consider as the first electrochemical sensor, i.e., a modified electrode surface dedicated to a specific target analyte, was a platinum electrode, covered by a protective membrane, the Clark electrode, for the determination of O2 in blood.The first biosensor was based on the determination with such Clark electrode of O2 depletion induced by glucose oxidase activity in the presence of glucose.These two examples show the importance of platinum as electrode material. It will be seen below that gold was also widely used for the development of chemically modified electrodes, especially due to the strong interaction with thiol-functionalized organic molecules allowing the formation of self-assembled monolayers (SAM). ... 

Kelley, R. L. and C. A. Reddy. 1986. Identification of glucose oxidase activity as the primary source of hydrogen peroxide production in ligninolytic cultures of Phanerochaete chrysosporium. Arch. Microbiol. 144 248-253. 

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