Glucose hydrogen peroxide

Glucose oxidase 1.1.3.4 Glucose Hydrogen peroxide Oxidation of a chromogen... 

Pizzariello, A., Stredansky. M.. and Miertus, S. (2002) A glucose/hydrogen peroxide biofuel cell that uses oxidase and peroxidase as catalysts by composite bulk-modified bioelectrodes based on a solid binding matrix. Bioelectrochemistry, 56 (1-2), 99-105. 

GOx + peroxidase Glucose hydrogen peroxide Amphiphilic polypyrrole 181... 

Fig. 5. Detection methods for glucose enzyme electrode based on (a) oxygen, (b) hydrogen peroxide, and (c) a mediator. See text.

The hydrogen peroxide produced in the glucose oxidase catalyzed reaction has an antibacterial action. If the presence of hydrogen peroxide is undesirable in the product, catalase is added to remove the peroxide. 

In presence of the enzyme glucose oxidase, an aqueous solution of glucose undergoes oxidation to gluconic acid with formation of hydrogen peroxide which can be determined by anodic oxidation at a fixed potential. 

When the electrode is placed in an aqueous solution of glucose which has been suitably diluted with a phosphate buffer solution (pH 7.3), solution passes through the outer membrane into the enzyme where hydroxen peroxide is produced. Hydrogen peroxide can diffuse through the inner membrane which, however, is impermeable to other components of the solution. The electrode vessel contains phosphate buffer, a platinum wire and a silver wire which act as electrodes. A potential of 0.7 volts is applied to the electrodes (the apparatus shown in Fig. 16.17 is suitable) with the platinum wire as anode. At this electrode the reaction H202->02 + 2H+ +2e takes place, and the oxygen produced is reduced at the silver cathode ... 

A second principle used widely for glucose analysis, is that of the oxidation of glucose enzymatically, mediated by the action of glucose oxidase with the formation of gluconic acid and hydrogen peroxide (22). In this procedure it is the hydrogen peroxide which is usually assayed for determination of glucose. This method suffers from the action of inhibitors which occur, particularly with patients in a diabetic coma and these need to be removed. 

A bi-enzymatic system (glucose oxidase -I- HRP) was also used to catalyze the synthesis of phenolic polymers. The polymerization of phenol, albeit in moderate yield, was accomplished in the presence of glucose avoiding the addition of hydrogen peroxide (Scheme 2 ), which was formed in situ by the oxidation of glucose catalyzed by glucose oxidase. 

In recent years considerable attention has focused on the mechanisms of oxidative damage to the cornea. In a study to determine the interaction of ascorbate, hydrogen peroxide and oxygen in the eye, Riley et al. (1986) found that ascorbate promoted corneal swelling when isolated corneas were perfused with glucose-deficient medium. This was due to the rapid oxidation of... 

Several studies have demonstrated the production of mucosal damage and/or increased mucosal permeability by hydrogen peroxide, the hydroxyl radical, or by installation of xanthine or glucose oxidase (Gregaard et al., 1982 Parks et al., 1984 Joubert-Smith et al., 1991 Kohen etal., 1992). 

---