Oxidase glucose

In a study of the periodate oxidation of r -glucose oxidase from Aspergillus niger, 50% of the carbohydrate was removed with little effect on enzymic activity. Gel permeation chromatography results suggested that the oxidized enzyme exists as a complex oligomerizing system. 

Lysozymes.—Three derivatives of hen egg-white lyso me have been prepared 2- chlorobenzyloxycarbonyl-lysozyme, 3-(4-methylbenzyl)-(refiuced lysozyme) and 2-chlorobenzyloxycarbonyl-5 -(4-methylbenzyl)-(reduced lysozyme). On treatment of the derivatives with anhydrous hydrogen fluoride, fully active lysozyme could be recovered, with yields of 23, 12, and 7.4% respectively. The properties of the recovered lysozyme were identical to those of the native enzyme, and crystals of the two materials were indistinguishable. 

The chemical modification of hen egg-white lysozyme by AT-bromosuccinimide has been studied kinetically using the stopped-fiow method and previous results have been confirmed. One most rapidly reacting L-tryptophan residue (probably Trp-62) was clearly distinguished, by its rate of modification, from four other residues. The residue could be protected by ethylene glycol, chitin, 2-acetamido-2-deoxy-D-glucose, or chitotriose, but not by D-glucono-1,4-lactone. 

HofejSf, C. HaSkovec, and J. Kocourek, Biochim. Biophys. Acta, 1978, 532, 98. B. Solomon, N. Lotan, and E. Katchalski-Katzir, Biopolymers, 1977, 16, 1837. 

The properties and composition of the complex formed between purified lysozyme and flavoprotein have been investigated.  

As discussed in section 8.3.7, catalase is frequently used together with glucose oxidase in many of the food applications of the latter however, the principal potential application of glucose oxidase in dairy technology is for the in situ production of HjOj, for which the presence of catalase is obviously undesirable. 

Glucose oxidase (GO) catalyses the oxidation of glucose to gluconic acid (via gluconic acid-d-lactone) according to the following reaction  

In the food industry, glucose oxidase has four principal applications  

Removal of residual trace levels of glucose. This application, which is particularly useful for the treatment of egg white prior to dehydration (although alternative procedures using yeast fermentation are used more commonly), is of little, if any, significance in dairy technology. 

Removal of trace levels of oxygen. Traces of oxygen in wines and fruit juices cause discolouration and/or oxidation of ascorbic acid. Chemical 

GO often is used in solution phase chemical reactions as well as being immobilized on dip-sticks and electrodes. Although its overall clinical usage is widespread, its use as conjugated to antibodies in enzyme-linked assay systems is minor compared to the popularity of other enzymes like horseradish peroxidase and alkaline phosphatase. 

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Figure 11.39 summarizes the reactions taking place in this amperometric sensor. FAD is the oxidized form of flavin adenine nucleotide (the active site of the enzyme glucose oxidase), and FAD1T2 is the active site s reduced form. Note that O2 serves as a mediator, carrying electrons to the electrode. Other mediators, such as Fe(CN)6 , can be used in place of O2. 

Sittampalam, G. Wilson, G. S. Amperometric Determination of Glucose at Parts Per Million Levels with Immobilized Glucose Oxidase, /. Chem. Educ. 1982, 59, 70-73. 

This experiment describes the use of a commercially available amperometric biosensor for glucose that utilizes the enzyme glucose oxidase. The concentration of glucose in artificial... 

Commercially available kits for monitoring blood-glucose use an amperometric biosensor incorporating the enzyme glucose oxidase. This experiment describes how such monitors can be adapted to the quantitative analysis of glucose in beverages. 

Chemical kinetic methods have been applied to the quantitative analysis of a number of enzymes and substrates.One example, is the determination of glucose based on its oxidation by the enzyme glucose oxidase. ... 

Bateman, Jr. R. C. Evans, J. A. Using the Glucose Oxidase/Peroxidase Systems in Enzyme Kinetics, /. Chem. Educ. 1995, 72, A240-A241. 

Another group of compounds called oxygen scavengers retard oxidation by reducing the available molecular oxygen. Products in this group are water soluble and include erythorbic acid [89-65-6] C HgO, and its salt sodium erythorbate [6381-77-7] C HgO Na, ascorbyl pahnitate [137-66-6] 22 38 7 ascorbic acid [50-81-7] C HgO, glucose oxidase [9001-37-0] and sulfites (23). 

Chemiluminescence and bioluminescence are also used in immunoassays to detect conventional enzyme labels (eg, alkaline phosphatase, P-galactosidase, glucose oxidase, glucose 6-phosphate dehydrogenase, horseradish peroxidase, microperoxidase, xanthine oxidase). The enhanced chemiluminescence assay for horseradish peroxidase (luminol-peroxide-4-iodophenol detection reagent) and various chemiluminescence adamantyl 1,2-dioxetane aryl phosphate substrates, eg, (11) and (15) for alkaline phosphatase labels are in routine use in immunoassay analyzers and in Western blotting kits (261—266). 

Parameter Cholesterol oxidase (CO) Cholesterol esterase (CE) Glucose oxidase (GOD) Peroxidase (POD)... 

Multienzyme Electrodes. Coupling the reactions of two or more immobilized enzymes increases the number of analytes that can be measured. An electro-inactive component can be converted by an enzyme to a substrate that is subsequentiy converted by a second enzyme to form a detectable end product (57). For example, a maltose [69-79-4] sensor uses the enzymes glucoamylase and glucose oxidase, which convert... 

Dried Whole Egg and Yolk. Dried plain whole egg and yolk products are either dried as is, or have the glucose removed to improve stabiHty and shelf life of the product. Glucose is removed before drying by use of glucose oxidase or by yeast fermentation (see Yeasts). Bacterial fermentation is not used because of off-flavor and off-odor development. 

Entrapment of biochemically reactive molecules into conductive polymer substrates is being used to develop electrochemical biosensors (212). This has proven especially useful for the incorporation of enzymes that retain their specific chemical reactivity. Electropolymerization of pyrrole in an aqueous solution containing glucose oxidase (GO) leads to a polypyrrole in which the GO enzyme is co-deposited with the polymer. These polymer-entrapped GO electrodes have been used as glucose sensors. A direct relationship is seen between the electrode response and the glucose concentration in the solution which was analyzed with a typical measurement taking between 20 to 40 s. 

E-number and generic name, eg, lysozyme or glucose oxidase. AMEEP has defined Good Manufacturing Practice (GMP) for microbial food enzymes. 

Glucose oxidase (from Aspergillus niger) [9001-37-0] Mf 186,000, [EC 1.1.3.4]. Purified by dialysis against deionized water at 6° for 48hours, and by molecular exclusion chromatography with Sephadex G-25 at room temperature. [Holt and Cotton J Am Chem Soc 109 1841 1987.]... 

Enzymes are proteins of high molecular weight and possess exceptionally high catalytic properties. These are important to plant and animal life processes. An enzyme, E, is a protein or protein-like substance with catalytic properties. A substrate, S, is the substance that is chemically transformed at an accelerated rate because of the action of the enzyme on it. Most enzymes are normally named in terms of the reactions they catalyze. In practice, a suffice -ase is added to the substrate on which die enzyme acts. Eor example, die enzyme dial catalyzes die decomposition of urea is urease, the enzyme dial acts on uric acid is uricase, and die enzyme present in die micro-organism dial converts glucose to gluconolactone is glucose oxidase. The diree major types of enzyme reaction are ... 

Glucose oxidase, which catalyzes the oxidation of glucose to gluconic acid. 

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