Catechol adaptation

Figure 7.6 Metabolism of MDMA in humans. Abbreviations CYP2D6, cytochrome P450 2D6 CYP3A4, cytochrome P450 3A4 COMT, catechol-O-methyltransferase. (Adapted from de la Torre and co-workers.56)...

In a static-culture-flask screening test, naphthalene (5 and 10 mg/L) was statically incubated in the dark at 25 °C with yeast extract and settled domestic wastewater inoculum. After 7 d, 100% biodegradation with rapid adaptation was observed (Tabak et al, 1981). In freshwater sediments, naphthalene biodegraded to c/5-1,2-dihydroxy-1,2-dihydronaphthalene, 1-naphthol, salicylic acid, and catechol. 

Figure 10.11 Voltammetry of 0.45 mM catechol in 0.1 M H2S04 at polished GC (a) after polishing (b) after first, second, fourth, and seventh activation cycles (cycled to 1.78 V vs. Ag QRE at 0.2 V/s) (c) dashed voltammogram was obtained 35 min after activation. [Adapted from Ref. 44.]...

Figure 22.18. Quinone redox cycling. A substituted catechol is shown as an example. [Adapted from Squadrito, G. L., Cueto, R., Dellinger, B., and Pryor, W. A. Free Radic. Biol. Med. 31, 1132-1138, 2001.]...

Fig. 9D.4 Preferred conformation of dimer B2-3 - O-gallate (B2G) and suggested conformational arrangements of the oenin intercalated between the galloyl ester group and catechol ring B of B2G (adapted from Berke and de Freitas 2005)...

Titanosilicalite (TS-1)[165,166], a highly siliceous MFI type zeolite in which 0.1 to 2.5% of the Si atoms are replaced by Ti, is the most successful example for the use of isomorphously substitited zeolites. As a consequence of the high Si/Al ratio of TS-1 the material contains only a negligible concentration of strong Bronsted acid sites. In fact, the presence of acid sites is detrimental to the selectivity of the catalysts, as discussed below. TS-1 has been found to be a selective oxidation catalyst for a wide variety of reactions such as the conversion of alkenes to epoxides [167], alcohols to aldehydes [168], alkanes to secondary alcohols and ketones [169,170], phenol to hydroquinone and catechol [171] and amines to hydroxylamines [ 172]. A schematic representation of the chemistry is given in Fig. 7 which is adapted from ref [17]. 

Fig. 13. Formation of vanillylmandelic acid from norepinephrine and epinephrine [adapted from Gidow et ti. (G12)]. (a) Methylation of the amino group of norepinephrine (h) methylation through catechol-O-methyltransferase and (c) monoamine oxidation + aldehyde oxidation.

Adapted from Table 3, Hydroquinone, Resorcinol and Catechol, by J. Varagnat, Kirk-Othmer Encl.,vol. 13,p47,3rd. Edn., 1981, by permission of Wiley-Interscience). 

Figure 26. Speciation of lead in a soil affected by alkyllead compounds used as antiknock additives in gasoline. The soil EXAFS spectrum (solid) is compared to model spectra from a library of lead compounds. This comparison identifies salicylate and catechol functional groups as the predominant complexing chelates for divalent Pb. Adapted from Manceau et al. (1996). Figure continued on facing page.)...

Fe L = bis(bidentate) catecholamide). " The M4L6 assemblies contain four metal centers, each of which can adapt either a A or A configuration. Only homochiral isomers of the assemblies form, that is, each assembly is either A, A,A,A- or A,A,A,A-configured and does not racemize. In these assemblies the metal atoms are located at the vertices of the tetrahedron and six bis-bidentate naphthalene-based catechol amide ligands span the edges (Figure 53). 

Figure 5. The biocatalytic pathway (boxed arrows) created for microbial conversion of D-glucose into cis, cw-muconate from the perspective of the biochemical pathways from which the enzymes were recruited. Conversion of D-glucose into DHS requires transketolase (tkt) from the pentose phosphate pathway and DAHP synthase (aroF, aroG, aroH)y DHQ synthase aroB and DHQ dehydratase aroD) from the common pathway of aromatic amino acid biosynthesis. Conversion of DHS into catechol requires DHS dehydratase (aroZ, enzyme A) from hydroaromatic catabolism, protocatechuate decarboxylase aroY, enzyme B), and catechol 1,2-dioxygenase (caM, enzyme C) from the benzoate branch of the p-ketoadipate pathway. (Adapted and reproduced with permission from ref. 21.)...

SCHEME 10.5 Oxidation of 3,5-di-r-butyl-catechol with H2O2 to the corresponding o-quinone product catalyzed by MP-11 Tb-mesoMOF. (Adapted from Ref. [101] with permission of American Chemical Society. Copyright 2011.)... 

Fig. 3.9 The LLCT lowest absorption band, and its solvatochromism, for Pt(bpy)(3,5-di- Bu-catecholate). Normalised absorption spectra recorded in solvents of different polarity 1 methanol, 2 ethanol, 3 CH3CN, 4 DMSO, 5 DMF, 6 acetone, 7 CH2CI2, and 8 CHCI3 Adapted with permission from Ref. [15], Copyright 2010 American Chemical Society...

Figure 4.5. Formation of guaiacol, catechol, and other compounds from vanillic acid by Streptomyces isolated from corks. Adapted from Alvarez-Rodriguez et al. (2003).

Pyrocatechase occurs in aerobic microorganisms Pseudomonas, Vdmo, Mycobacterium) as part of a network of enzymes which catalyze the oxidative degradation of aromatic compounds to succinate and acetyl-CoA (Fig. 1) (182,313,433,674,693,698,759). These processes have been extensively studied by means of adaptive phenomena, and by chemical isolation of products formed by living cells (63,234-236,238,291,423,676-678,690, 8). The pyrocatechase step consists in oxidation of catechol to m,m-muconic acid (equation 4), (237,322) ... 

Pyrocatechase has been isolated from Pseudomonas adapted to anthranilic acid or to tryptophan (321,322,591,695,716). The enzyme catalyzes the consumption of one molecule of oxygen per molecule of catechol (CjHjOj) oxidized (321,322) and the product, cis,m-muconic acid (CeH(04), contains two atoms of oxygen more than catechol. 

Fig. 22 Modelling ability of the optimized ANN for the multicomponent determination of phenolic compounds present in wine. Training filled circles), external test empty circles) and spiked wine samples empty diamonds) set adjustments of the expected concentration vs. obtained concentrations for top) catechol, middle) caffeic acid and bottom) ( )-catechin. Dashed lines correspond to theoretical diagonal line. Error bars correspond to five different retrainings with random reinitialization of weights for the final architecture. Polyphenolic structures attached to the graphs and fitted regression lines for the three subsets stated on top of each plot. Adapted from [63], with permission from the Royal Society...

Pyrocatechase is an enzyme widely distributed among bacteria. It catalyzes an oxidation of o-dihydroxybenzene, and is named according to the traditional name of the substrate, pyrocatechol. Pyrocatechol, more commonly known by the abbreviated designation catechol, is an intermediate in the metabolism of many aromatic compounds, including mandelic acid, nitrobenzoic acid, anthranilic acid, and other compounds that may be converted to salicylic acid. Benzoic acid and phenol are also precursors of catechol. The best-studied enzyme is that obtained from a strain of Pseudomonas that can use tryptophan as a carbon source. The enzyme is formed adaptively when tryptophan, catechol, or any intermediate between the amino acid and catechol (Fig. 4) is used as a substrate for the cells (Suda et al., 1950). 

The 100-fold purified enzyme from Pseudomonas adapted to tryptophan appears to be homogeneous. It has a molecular weight of about 80,000. The activity is rapidly reduced to zero as the pH drops below 7, is maximal between pH 7 and pH 10, then drops rapidly at higher pH values. The affinity for catechol is very great the Km is about 5 x 10 M. The rate is increased only slightly when pure oxygen is substituted for air. 

Vibrio. They have also eliminated ]8, y-dihydroxyadipic acid as an intermediate, in the degradation of protocatechuic acid by Pseudomonas. The monolactone is a precursor of j3-ketoadipic acid in extracts of certain organisms adapted to protocatechuic acid thus, following decarboxylation, the catechol and protocatechuic pathways become identical. The roles of the lactones of j8-carboxymuconic acid are still not certain evidence for a lactone with an absorption spectrum different from known lactones was obtained with Nocardia extracts (Cain and Cartwright, 1960). 

Benzene, This simplest aromatic compound is utilized by a variety of bacteria as the sole source of carbon and energy in a mineral salts solution (Beerstecher, 1954, p. 189). In the rabbit and the human several hydroxylated intermediates have been identified (Porteus and Williams, 1949) phenol, 1,2-dihydroxybenzene (catechol), 1,4-dihydroxybenzene (quinol), and 1,2,4-trihydroxybenzene (hydroxyquinol). In bacteria, the fissioned ring product has been isolated as trans,trans-m xcomc acid (Kleinzeller and Fend, 1952 Wieland et al., 1958). Catechol is the probable immediate precursor of muconate, this conversion having been demonstrated repeatedly by (1) isolation of muconic acid, (2) simultaneous adaptation studies, and (3) experiments with the cell-free, ferro-enzyme pyrocatechase (Hayaishi and Hashimoto, 1950 Evans and Smith, 1951 Evans et al., 1951 Stanier and Ingraham, 1954). Two atoms of oxygen are added per molecule of catechol. Hayaishi and co-workers (1955) have shown by means of experiments with and and... 

Phenol itself is converted to catechol, quinol, and hydroxyquinol in the rabbit (Porteus and Williams, 1949), and to catechol by a gram-negative vibrio (Evans and Happold, 1939 Evans, 1947). A modified sequential monohydroxylation scheme was proposed by Wieland and co-workers (19S8) for Nocardia sp. on the basis of results using the simultaneous adaptation technique (Eq. 9). 

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