Peroxidase mimetic

PEROXIDASE-MIMETIC SENSOR FOR DETECTION OF ETHANOL IN LOW CONCENTRATIONS IN AQUEOUS SOLUTIONS... 

As shown below, the basic principles of peroxidase-mimetic sensor appliance operation are developed using the example of model peroxidase reaction of ethyl alcohol electrochemical oxidation to aldehyde. 

Studies on ethanol trace detection in aqueous solutions were carried out in an electrochemical cell of peroxidase-mimetic sensor of the potentiometric type, consisting of a reference electrode (Ag/AgCl) and a biomimetic electrode. Redistilled water was used for the background solution. The biomimetic electrode was prepared by adhering hematin-containing meroxidase mimetic to aluminum foil with Pattex adhesive [7, 8],... 

The peroxidase mimetic and its enzymatic analog consist of two components active and carrying. The carrier represents neutral activated aluminum oxide, on which active site (hematin with 8.6 wt.% iron), produced by Sigma Company, is applied [11, 12], The biomimetic was synthesized according to the known technique. 

Figure 8.12 The apparent mechanism of peroxidase-mimetic electrode operation in electrocatalytic mode.

To check these suggestions, the authors conducted an experiment with a peroxidase-mimetic sensor prepared on a new aluminum electrode under conditions corresponding to one of the minima in Figure 8.14. As shown by the plot of this experiment (point A in Figure 8.14), the minimum at C2H5OH concentration equal 10-3wt.% depends on aluminum foil conditions for a fresh electrode a sharp, jump-like increase of the potential is detected. 

Cyclic seleninate esters have been implicated in catalytic cycles in which diselenides act as glutathione peroxidase mimetics <2003JA13455> (see Section 9.15.11). Treatment of the diselenides 48 and 49 with excess / -rt-butylbydro-peroxide leads to the formation of the first unsubstituted isolable cyclic seleninates 50 and 51 (Equations 9 and 10). The six-membered ring compound 50 proved to be a less effective catalyst than 51 in the former reactions. 

Liang, L., Ge, S., Li, L., Liu, R, Yu, J., 2015. Microfluidic paper-based multiplex colorimetric immunodevice based on the catalytic effect of Pd/Pe304 C peroxidase mimetics on multiple chromogenic reactions. Analytica Chimica Acta 862 (0), 70-76. 

Lyon, J. L. and Stevenson, K. J. 2009. Peroxidase mimetic activity at tailored nanocarbon electrodes. ECS Trans. 16 1-12. 

The area between enzymatic and chemical catalyses, associated with simulation of biochemical processes by their basic parameters, is accepted as mimetic catalysis. The key aspect of the mimetic catalyst is diversity of enzyme and biomimetic function processes, which principally distinguishes the mimetic model from traditional full simulation. Based on the analysis of conformities and diversities of enzymatic and chemical catalysis, the general aspects of mimetic catalysis are discussed. An idealized model of the biomimetic catalyst and the exclusive role of the membrane in its structural organization are considered. The most important achievements in the branch of catalysis are shown, in particular, new approaches to synthesis and study of biomimetic catalase, peroxidase and monooxidases reactions. 

The investigations of catalase-mimetic sensors allow continuation of studies in the field of biomimetic sensors of peroxidase type. 

Many peroxovanadates have potent insulin-mimetic properties [1,2]. Apparently, this functionality derives from the ability of these compounds to rapidly oxidize the active site thiols found in the group of protein tyrosine phosphatases that are involved in regulating the insulin receptor function [3], The discovery of vanadium-dependent haloperoxidases in marine algae and terrestrial lichens provided an additional stimulus in research toward obtaining functional models of peroxidase activity, and there is great interest in duplicating the function of these enzymes (see Section 10.4.2). 

Similarly to Mb, Hb is also active in the catalytic oxidation of substrates by hydrogen peroxide, with rates and general behavior comparable with those of Mb. In particular, a number of research reports showed that Hb exhibits oxidizing activities and can be used as a mimetic peroxidase to catalyze the oxidation reactions of aromatic compounds [180-182], aniline [183, 184], lipids [185], styrene [186], and sulfides [187]. Again, although the activity of Hb is not comparable with... 

Zhang Y-Y, HuX, Tang K, Zou G-L (2006) Immobilization of hemoglobin on chitosan films as mimetic peroxidases. Process Biochem 41 2410-2416... 

It has been generally assumed that the S-enantiomers of sympatho-mimetics are practically inert and therefore lack desired or deleterious effects. However, the current data clearly indicate that the distomers do possess some activities, which may oppose those of the respective eutomers. For instance, S-isoprenaline (distomer) administration to asthmatic patients ( = 10) caused a substantial decrease in FEVi in 2 patients and increased reactivity to histamine 7h after inhalation [103]. Similarly, S-albuterol causes activation of human eosinophils, suggesting proinilammatory properties for this enantiomer. Both R-albuterol and racemic albuterol inhibited the IL-5 induced superoxide generation and eosinophil peroxidase release. In contrast, S-albuterol significantly enhanced the superoxide and peroxidase release by eosinophils [102,106]. 

Although, salen Mn complexes for therapeutic use were originally conceived as SOD mimetics, it soon became clear that EUK-8 also exhibited catalase activity, the ability to metabolize hydrogen peroxide (75). The catalase activity of EUK-8 was not unexpected, since Mn porphyrins had been studied as catalase models by the Meunier laboratory (16) and, like the porphyrins, salen ligands form stable complexes with Mn(III) (6). As described previously (77), similar to that of mammalian heme-iron based catalases (78), the catalase activity of salen Mn complexes is not saturable with respect to hydrogen peroxide. As has been reported for protein catalases (18), salen Mn complexes exhibit peroxidase activity, in the presence of an electron donor substrate, as an alternative to a catalatic pathway. This supports the analogy between the behavior of these mimetics and that of catalase enzymes, and is consistent with the following mechanistic scheme (76,17) ... 

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