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Pyrocatechase and

Both of the oxygen atoms incorporated into catechol have been shown639 by labeling studies to be derived from molecular oxygen. Pyrocatechase and other related oxygenases are known to require either copper or iron for maximum activity. An efficient, nonenzymatic oxidation of catechol to s,os-muconate with molecular oxygen activated by cuprous chloride has been recently presented as a model reaction for pyrocatechase.649... [Pg.383]

Fig. 2. Visible spectra of native pyrocatechase and the pyrocatechase-catechol complex (SO mM Tris-acetate buffer pH 8)... Fig. 2. Visible spectra of native pyrocatechase and the pyrocatechase-catechol complex (SO mM Tris-acetate buffer pH 8)...
The products of a 60-hour reaction at room temperature were 3.5-DTBQ (24 %), DBMUA (45 %) and BUP (6 %). As TCQ is not oxidized, the TCC ligand is apparently displaced by 3,5-DTBC from the coordination sphere before any oxidation takes place. Extensive intradiol cleavage occurs with the incorporation of one 0-atom, similarly to a ruthenium-catalyzed reaction [103] but in contrast to pyrocatechase and its iron [105] and copper models [32], where 2 0-atoms are inserted. [Pg.283]

The dioxygenases, which incorporate two atoms of oxygen into one molecule of the substrate, are enzymes which are frequently involved in the cleavage of bonds in an aromatic ring. Typical of these are homogentisate oxidase and L-tryptophan oxidase (L-tryptophan pyrrolase) and two bacterial oxygenases pyrocatechase and metapyrocatechase. ... [Pg.154]

Figure 16. Correlation between the or j values of substituted catechols for different pyrocatechases and Hammett substitutent constants [92]. Figure 16. Correlation between the or j values of substituted catechols for different pyrocatechases and Hammett substitutent constants [92].
These results were taken as evidence that pyrocatechase and probably all other phenolytic oxygenases utilize two atoms of molecular oxygen for additive oxidation, and that the oxygen atoms in the water molecule were not utilized as a source of oxygen added to the substrate. [Pg.9]

The evidence from Suda s laboratory indicates that in pyrocatechase and homogentisic oxidase the iron is bound to a tyrosine residue. In tryptophan pyrrolase the iron is present as heme. In the case of reactions involving bonds adjacent to a catechol or o-amino phenol group, the hydroxyl or amino group away from the bond to be attacked may participate in the iron complex. In all cases the iron may be assumed to be bound in a complex that permits very little dissociation (as measured by exchange with free ferrous ions) at neutral or alkaline pH values. [Pg.122]

On the other hand, Hayaishi and his associates found that the two atoms of oxygen incorporated into catechol by the action of pyrocatechase were both derived from molecular oxygen3 [Eq. (2)]. [Pg.147]

As in the cases of phenolase and pyrocatechase, respectively, oxygenases catalyze the incorporation of either one or two atoms of molecular oxygen into their substrates. Therefore, they are classified into two major groups, monooxygenases and dioxygenases1S). [Pg.148]

Similar but not identical pyrocatechases have been purified to homogeneity from various microorganisms including Brevibacterium fuseum P-13112,113 and... [Pg.153]

Spectral Properties. The absorption spectra of these three pyrocatechase are very similar to each other. A concentrated solution of the enzyme shows a distinct red color with a broad absorption between 390 and 650 nm. The peak is at about 440 nm and the molecular absorbance at 440 nm is estimated to be 4,670s5. The trivalent iron bound to the enzyme is responsible for the visible absorption since the apo-enzyme shows neither significant absorption in the visible region nor enzyme activity which is restored upon reconstitution56. The visible absorption also de-... [Pg.153]

Table 4. Substrate specificity of pyrocatechases from Pseudomonas, Brevibacterium and Acinetobactor... Table 4. Substrate specificity of pyrocatechases from Pseudomonas, Brevibacterium and Acinetobactor...
Serological Properties. Antisera prepared against purified preparation of Acineto-bactor pyrocatechase cross-react and inhibit the enzyme activity in the crude extracts prepared from other strains of Acinetobactor calcoaceticus, but fail to cross-react and inhibit isofunctional enzymes prepared from strains of Pseudomonas, Nocardia, and Alcaligenes114. ... [Pg.158]

A few [VO(OMe)(/8-diketonato)]2 and [VO(L)]2 complexes (L = polydentate O-coordinating ligands) also have a high catalytic activity for the oxygenation of catechols (namely 3,5-di-f-butyl-1,2-dihy droxybenzene)554 and this reaction was considered similar to the one catalyzed by pyrocatechase. [Pg.510]

Tsuji and coworkers reported that copper(I) chloride in the presence of pyridine, methanol and dioxygen promotes the stoichiometric oxidation of pyrocatechol to methyl muconate.606 Labeling lg02 studies have shown that only one atom of the dioxygen molecule is incorporated in the substrate, while the other one is transformed into water as in enzymic monooxygenases (equation 275)607 (and not as in dioxygenases, viz. pyrocatechase). This reaction has been shown by Rogic et al. to proceed via two steps (equation 276).580,58 ... [Pg.393]

These enzymes are red in color and contain ferric ion as the sole cofactor. Two types of enzymes have been isolated from various bacteria — pyrocatechases which catalyze catechol cleavage and protocatechuate 3,4-dioxygenases which cleave 3,4-dihydroxybenzoate (protocatechuate). The pyrocatechases have molecular weights in the 60.000-90.000 dalton range9-11) the enzyme from Pseudomonas arvilla (MW 63.000) has two subunits with the molecular form a0Fe9), while the enzyme from Acinetobacter calcoaceticus (MW 85.000) is a dimer of the form (aFe)210). [Pg.40]

We have also found carboxylates to be weak inhibitors (Kj 5 mM) of these dioxygenases44) upon binding, the carboxylates cause a red shift in the absorption maximum. For example, the addition of benzoate to pyrocatechase shifts from 458 nm to 5.05 nm. Only dicarboxylates such as succinate and glutarate effect this spectral change for protocatechuate 3,4-dioxygenase ( ,ax 530 nm). Presumably,... [Pg.52]

Fig. S. A and B. Visible spectra of (A) 4-nitrocatechol at pH 8.S and the pyrocatechase-4-nitro-catechol complex (50 mM Tris-acetate pH 8) (B) 4-nitrocatechol at pH 13 and the protocatechuate 3,4-dioxygenase-4-nitrocatechol complex (50 mM Tris-acetate pH 8)... Fig. S. A and B. Visible spectra of (A) 4-nitrocatechol at pH 8.S and the pyrocatechase-4-nitro-catechol complex (50 mM Tris-acetate pH 8) (B) 4-nitrocatechol at pH 13 and the protocatechuate 3,4-dioxygenase-4-nitrocatechol complex (50 mM Tris-acetate pH 8)...

See other pages where Pyrocatechase and is mentioned: [Pg.242]    [Pg.212]    [Pg.20]    [Pg.46]    [Pg.123]    [Pg.242]    [Pg.212]    [Pg.20]    [Pg.46]    [Pg.123]    [Pg.153]    [Pg.153]    [Pg.157]    [Pg.159]    [Pg.161]    [Pg.165]    [Pg.165]    [Pg.306]    [Pg.40]    [Pg.48]    [Pg.51]    [Pg.51]    [Pg.53]    [Pg.54]    [Pg.54]   


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