Adaptive enzyme pyrocatechase

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... 

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. 

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). 

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