Horseradish peroxidase reaction

Substrate 150 xL/well Substrate for horseradish peroxidase reaction 0.4mM TMB (tetramethylbenzidine), 1.3mM H2O2 in 100mM sodium acetate buffer, pH 5.5... 

For equation systems of low dimension, the investigation of the inherent timescales can be carried out through a non-dimensionalisation process. Small parameters can then often be identified indicating fast variables. A discussimi of non-dimensionalisation procedures for a simplified 4-variable model describing the horseradish peroxidase reaction can be found in Chap. 12 of Scott (1990). The 4-variable model can be described by the following reaction steps ... 

It should be noted that a number of different enzyme preparations can now be purchased directly from manufacturing chemists. It must be emphasised that the activity of an enzyme, whether purchased or prepared in the laboratory, may vary between rather wide limits. The activity is dependent on the source of the enzyme, the presence of poisons and also on the temperature. It appears, for example, that the quality of horseradish peroxidase depends upon the season of the year at which the root is obtained from the ground. It cannot be expected therefore that all the experiments described below will work always with the precision characteristic of an organic reaction proceeding under accurately known conditions. 

Catalytic oxidation of isobutyraldehyde with air at 30—50°C gives isobutyric acid [79-31-2] ia 95% yield (5). Certain enzymes, such as horseradish peroxidase, cataly2e the reaction of isobutyraldehyde with molecular oxygen to form triplet-state acetone and formic acid with simultaneous chemiluminescence (6). 

A method of detecting herbicides is proposed the photosynthetic herbicides act by binding to Photosystem II (PS II), a multiunit chlorophyll-protein complex which plays a vital role in photosynthesis. The inhibition of PS II causes a reduced photoinduced production of hydrogen peroxide, which can be measured by a chemiluminescence reaction with luminol and the enzyme horseradish peroxidase (HRP). The sensing device proposed combines the production and detection of hydrogen peroxide in a single flow assay by combining all the individual steps in a compact, portable device that utilises micro-fluidic components. 

H2O2 was 2.9 x 10-6 M. A requirement for O2 could not be detected, suggesting that 02 is not involved in the luminescence reaction. The luciferase was found to be a peroxidase that catalyzes peroxidation of the luciferin, and it can be substituted with horseradish peroxidase. 

One of the most used systems involves use of horseradish peroxidase, a 3-diketone (mosl commonly 2,4-pentandione), and hydrogen peroxide." " " Since these enzymes contain iron(II), initiation may involve decomposition of hydrogen peroxide by a redox reaction with formation of hydroxy radicals. However, the proposed initiation mechanism- involves a catalytic cycle with enzyme activation by hydrogen peroxide and oxidation of the [3-diketone to give a species which initiates polymerization. Some influence of the enzyme on tacticity and molecular... 

In hiphasic water/1L mixtures, the latter can he used as immohilization systems. This idea was used for the synthesis of conducting polyanihne hy IL-immohilized horseradish peroxidase [68]. Tuning the IL hydrophohicity hy changing the anionic component allowed the increase in the yield of the product hy altering the affinity of the product to the IL. After completion of the reaction, the IL phase was separated, facilitating the recovery of the enzyme. 

Martmez-Parra, J. and Munoz, R., An approach to the characterization of betanine oxidation catalyzed by horseradish peroxidase, J. Agric. Food Chem., 45, 2984, 1997. Martmez-Parra, J. and Munoz, R., Characterization of betacyanin oxidation catalyzed by a peroxidase from Beta vulgaris L. roots, J. Agric. Food Chem., 49, 4064, 2001. Ashie, l.N.A. Simpson, B.K., and Smith, J.P., Mechanisms for controlling enzymatic reactions in foods, Crit. Rev. Food Sci. Nutr., 36, 1, 1996. 

Baek, H.K. and van Wart, H.E., Elementary steps in the reaction of horseradish peroxidase with several peroxides kinetics and thermodynamics of formation of compound 0 and compound I, J. Am. Chem. Soc., 114, 718-725, 1992. 

In the reaction of luminol, hydrogen peroxide, and horse radish peroxidase 122> the chemiluminescence intensity is proportional to the square of luminol radical concentration. The lifetime of these luminol radicals was found by ESR techniques to be about 10 sec. Titration studies revealed that luminol acts as two-electron donor during the reduction of a hydrogen peroxide-horseradish peroxidase complex. The enzyme is not involved in the reaction step leading directly to light emission. This step is formulated as... 

For a long time one question remained unanswered the efficiency of the Fenton reaction as the in vivo producer of hydroxyl radicals due to the low rate of Reaction (2) (the rate constant is equal to 42.11 mol 1 s 1 [18]). It is known that under in vitro conditions the rate of Fenton reaction can be sharply enhanced by chelators such as EDTA, but for a long time no effective in vivo chelators have been found. From this point of view new findings obtained by Chen and Schopfer [19] who found that peroxidases catalyze hydroxyl radical formation in plants deserve consideration. These authors showed that horseradish peroxidase (HRP) compound III is a catalyst of the Fenton reaction and that this compound is one to two orders of magnitude more active than Fe EDTA. 

Fig. 8. Schematic presentation of a enzyme linked immunosorbent assay (ELISA). An antigen ( ) is immobilized on the surface of a microtiter plate and incubated with its antibody (abl). A second antibody (ab2) with a covalently linked enzyme ( , e.g., horseradish peroxidase) binds to the primary one and catalyzes a color reaction with its enzyme. All incubations are separated by washing steps...

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