Peroxidase electrodes

It is important to compare the catalytic properties of Prussian blue with known hydrogen peroxide transducers. Table 13.2 presents the catalytic parameters, which are of major importance for analytical chemistry selectivity and catalytic activity. It is seen that platinum, which is still considered as the universal transducer, possesses rather low catalytic activity in both H202 oxidation and reduction. Moreover, it is nearly impossible to measure hydrogen peroxide by its reduction on platinum, because the rate of oxygen reduction is ten times higher. The situation is drastically improved in case of enzyme peroxidase electrodes. However, the absolute records of both catalytic activity... 

As pointed out by Gorton and co-workers [19,65], this process is usually referred to a direct electron transfer (DET), that is, when an electrode substitutes the electron donor substrates in a common peroxidase reaction cycle (Eqs. (17.8)-(17.10)). When an electron donor (SH), such as phenolic compounds and the catecholamines shown in Tables 17.2 and 17.4, is present in a peroxidase-electrode system, both processes can occur simultaneously [29,30,43,48,52-54] and the oxidized donor S is reduced electrochemically by the electrode as shown in the following reaction ... 

Yang L, Janie E, Huang T, Gitzen J, Kissinger PT, Vreeke M, Heller A. Applications of wired peroxidase electrodes for peroxide determination in liquid chromatography coupled to oxidase immobilized enzyme reactors. Analytical Chemistry 1995, 34, 1326-1331. 

Figure 8.11 Time dependencies of peroxidase electrode potential for 1 wt.% H202 and different CH3CHO concentrations - the product of electrochemical reaction (1 0.25 2 0.25 + 10 2 3 0.025 wt.% C2H5OH).

Yao T, Sato M, Kobayashi Y and Wasa T 1984 Row injection analysis for glucose by the combined use of an immobilized glucose oxidase reactor and a peroxidase electrode Ana/. Chim. Acta 165 291-6 Olsson B, Staibom E and Johansson G 1986 Determination of sucrose in the presence of glucose in a flow-injection system with immobilized multi-enzyme... 

T. Yao, M. Sato, Y. Kobayashi, and T. Wasa, Flow Injection Analysis for Glucose by the Combined Use of an Immobilized Glucose Oxidase Reactor and a Peroxidase Electrode. Anal. Chim. Acta, 165 (1984) 291. 

Clark et al. [32] have published in 1981 a method employing both enzymes in solution and potentiometrically measuring the concentration of the hydrogen peroxide formed. For an amperometric cholesterol assay Yao et al. [33, 34] used immobilized cholesterol esterase and cholesterol oxidase in a reactor assaying the hydrogen peroxide formed at a peroxidase electrode with the redox pair hexacyanoferrate(II)/hexacyanoferrate(III) as a mediator. 

Yifei, Y, and M. Shaolin. 1997. Bioelectrochemical responses of the polyaniline horseradish peroxidase electrodes. / Electroanal Chem 432 (1-2) 71. 

To characterize the electronic coupling in the peroxidase-electrode system, three ET reactions can be distinguished. The first is a one-electron transfer redox process reflecting the conversion between the ferro/ferri redox states, i.e., Fe /Fe . This process is not directly related to the catalytic cycle of peroxidase however, this reaction could be of interest for comparison with similar heterogeneous ET reactions of heme, heme-peptides, cytochrome c, or other heme-con-... 

The electrochemistry of peroxidases continues to be an intensive area of research. Critical evaluation of the results on the bioelectrochemistry of peroxidases leads to the conclusion that efficient direct electronic coupling between peroxidases and electrodes is possible. Rapid methods of genetic engineering of peroxidases [88-90] offer a new tool of tuning peroxidase-electrode interactions. This will facilitate the understanding of the electrochemistry of peroxidases as well as lead to the development of more selective and stable peroxidase-modified electrodes. 

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