Peroxidases as catalysts

In this test, oxygen from air is used for the enzymatic oxidation of (3-D-glucose in the presence of immobilized GOD to gluconic acid and hydrogen peroxide. Hydrogen peroxide can be determined by a second enzyme reaction. With horse radish peroxidase as catalyst o-phenylendiamine is oxidized by H2O2 to 2,3-diaminophenazine, which can be photometrically determined at 490 nm, thus establishing a quantitative relationship between active GOD sites and the intensity of the absorption band. 

PEROXIDASES AS CATALYSTS IN THE NATURAL BIOACUVE PLANT PHENOLICS... 

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. 

Dordick and coworkers [84] have shown that polyphenols can be successfully polymerized using ionic liquids as solvent and certain peroxidases as catalyst. They reasoned that RTILs would provide a threefold advantage over conventional solvents. First, the RTIL provides a nonaqueous environment that should show good solubility of the monomer and polymer second, the catalyst activity should... 

Phenol, the simplest and industrially more important phenolic compound, is a multifunctional monomer when considered as a substrate for oxidative polymerizations, and hence conventional polymerization catalysts afford insoluble macromolecular products with non-controlled structure. Phenol was subjected to oxidative polymerization using HRP or soybean peroxidase (SBP) as catalyst in an aqueous-dioxane mixture, yielding a polymer consisting of phenylene and oxyphenylene units (Scheme 19). The polymer showed low solubility it was partly soluble in DMF and dimethyl sulfoxide (DMSO) and insoluble in other common organic solvents. 

An experimental set-up such as that depicted in Fig. 5.12.C was also used by Nieman s group for the determination of free and total cholesterol in serum [37]. A solution of the enzyme (cholesterol oxidase) at pH 7 was forced through a microporous membrane. The pH gradient across the membrane (from 7 to 9) facilitated the enzymatic degradation of the analyte and subsequent diffusion of the hydrogen peroxide formed to the PMT in the reagent/sample stream in order to react with luminol in the presence of horseradish peroxidase as the catalyst at pH 9 —the copper chelate commonly used as catalyst for this purpose requires pH 11. The system per-... 

Adams, J.B., Harvey, A., and Dempsey, C.E. 1996. Regenerated and denatured peroxidase as potential lipid oxidation catalysts. Food Chem. 57 505-514. 

Oxometalloporphyrins were taken as models of intermediates in the catalytic cycle of cytochrome P-450 and peroxidases. The oxygen transfer from iodosyl aromatics to sulfides with metalloporphyrins Fe(III) or Mn(III) as catalysts is very clean, giving sulfoxides, The first examples of asymmetric oxidation of sulfides to sulfoxides with significant enantioselectivity were published in 1990 by Naruta et al, who used chiral twin coronet iron porphyrin 27 as the catalyst (Figure 6C.2) [79], This C2 symmetric complex efficiently catalyzed the oxidation... 

The peroxidase-catalyzed oxidation of 2,2 -azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), o-phenylene-diamine (PDA), and 3,3, 5,5 -tetramethylbenzidine (TMB) was found to be activated by tetrazole 2 and 5-aminote-trazole and weakly inhibited by 1,5-diaminotetrazole 33 <2004MI283>. Bhattacharya and Vemula studied the effect of heteroatom insertion in the side chain of 5-alkyl-177-tetrazoles on their properties as catalysts for ester hydrolysis at neutral pH <2005JOC9677>. l-(2-Iodophenyl)-177-tetrazole was successfully used in Heck reactions to give the cross-coupled products in excellent yield <2004TL4113>. 

Oxidation of 2-amino-3-cyanobenzodiazepinium chloride with hydrogen peroxide in the presence of peroxidase as a catalyst gave benzimidazole, which, unlike the benzodiazepine, was fluorescent, and this reaction has been applied to the determination of hydrogen peroxide by fluorimetry (80CPB2325). 

Oxidation of 2-amino-3-cyanobenzodiazepinium chloride with hydrogen peroxide in the presence of peroxidase as a catalyst gave a benzimidazole (80CPB2325). 

Naves AF, Carmona-Ribeiro AM, Petri DFS (2007) Immobilized horseradish peroxidase as a reusable catalyst for emulsion polymerization. Langmuir 23 1981-1987... 

In aprotic solvents, only oxygen and a base are necessary for the oxidation. In protic solvents a catalyst has to be present, in addition. As catalysts, enzymes such as horseradish peroxidase are frequently employed. 

In living cells, various oxidoreductases play an important role in maintaining the metabolism of living systems. Most of oxidoreductases contain low-valent metals as the catalytic center. In vitro enzymatic oxidoreductions have afforded functional organic materials.1 Recently, some oxidoreductases such as peroxidase, laccase, and bilirubin oxidase have received much attention as catalyst for the oxidative polymerizations of phenol and aniline derivatives to produce novel polyaromatics. 

In a mixture of water and water-miscible solvents such as acetone, 1,4-dioxane, and methanol, peroxidase could act as catalyst for oxidative polymerization of various phenol derivatives, yielding a new class of polyaromatics.4 The polymerization proceeds at room temperature, and during the polymerization, powdery polymers are often precipitated, which are readily collected after the polymerization. 

Lignin-degradating manganese(II) peroxidase was used as catalyst for the oxidative polymerization of various phenol derivatives such as guaiacol, o-cresol, and 2,6-dimethoxyphenol in the aqueous organic solvents.62... 

Model complexes of peroxidase were used as catalysts for the oxidative polymerization of phenols. Hematin, a hydroxyferriprotoporphyrin, catalyzed the polymerization of />ethylphenol in an aqueous DMF.63 Iron—A/,A/ -ethylenebis(salicylideneamine) (Fe—salen) showed high catalytic activity for oxidative polymerization of various phenols.64 The first synthesis of crystalline fluorinated PPO was achieved by the Fe—salen-catalyzed polymerization of 2,6-difluorophenol. Cardanol was polymerized by Fe— salen to give a cross-linkable polyphenol in high yields. 

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