Protocatechuate 2,3-dioxygenase

The enzyme has been obtained in crystalline form from Pseudomonas aeruginosa and shown to contain eight atoms of ferric iron per mole of enzyme, based on the molecular weight of 700,000 (Fujisawa and Hayaishi, 1968). The enzyme consists of eight identical subunits, each of which contains an atom of ferric ion that imparts a deep-red color to the protein and a substrate binding site (Fujisawa et aL, 1972a). A more recent study has shown that the enzyme consists of eight identical protomers of approxi- 

The enzyme obtained from Acinetobacter calcoaceticus, though quite similar in molecular weight, size, and iron content to that obtained from P. aeruginosa, possesses about one third of the specific enzymic activity (Hou et al, 1976). Protocatechualdehyde is a competitive inhibitor which binds P. aeruginosa protocatechuate 3,4-dioxygenase more effectively than the enzyme from Acinetobacter calcoaceticus. 

Lipoxygenase catalyzes the oxygenation of l,4-cis,a 5-pentadiene units on long-chain fatty acids to l-hydroxy-2,4-trans,cis-pentadienes. The addition of molecular oxygen involves removal of the central bisallylic hydrogen in the rate-limiting step, with the probable involvement of one iron atom on the enzyme. A possible mechanism of action is that a hydroperoxide 

When linoleic acid is added under anaerobic conditions a broad anistropic ESR signal occurs dii g 2. Thus it appears that lipoxygenase can exist in two forms (a) a resting form with a very low absorbance in the visible spectrum and no ESR signal and (b) an active form (after addition of linoleic acid hydroperoxide) with an increased optical absorbance and ESR signal at 6. The only other nonheme protein to exhibit a signal in the 6 

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Rhizobia. Taxa belonging to both the genera Rhizobium and Bradyrhizobium are capable of degrading simple aromatic compounds including benzoate (Chen et al. 1984) and 4-hydroxy-benzoate (Parke and Omston 1986 Parke et al. 1991). It has been shown that 4-hydroxyben-zoate hydroxylase is required for the transport of 4-hydroxybenzoate into the cell (Wong et al. 1994). In strains of Rhizobium trifolium, the metabolism of benzoate involves either 3,4-dihydroxybenzoate (protocatechuate) 3,4-dioxygenase (Chen et al. 1984), or catechol... 

Buchan A, LS Collier, EL Neidle, MA Moran (2000) Key aromatic-ring-cleavage enzyme, protocatechuate 3,4-dioxygenase, in the ecologically important marine Roseobacter lineage. Appl Environ Microbiol 66 4662-4672. 

Bull C, DP Ballou (1981) Purification and properties of protocatechuate 3,4-dioxygenase from Pseudomonas putida. A new iron to subunit stoichiometry. 7 Bio/ Chem 256 12673-12680. 

One last class of mononuclear non-haem iron enzyme that we have not yet considered, consists of the microbial superoxide dismutases with Fe(III) at their active site. The crystal structure of the E. coli enzyme shows a coordination geometry reminiscent of protocatechuate 3,4-dioxygenase, with four endogenous protein ligands, three His and one Asp residue, and one bound water molecule (Carlioz et ah, 1988). 

PROTOCATECHUATE 3,4-DIOXYGENASE CARBOXYPEPTIDASE A CARBOXYPEPTIDASE B CARBOXYPEPTIDASE C CARBOXYPEPTIDASE D Carboxypeptidase H (or, E),... 

R)-2-METHYLMALATE DEHYDRATASE NICOTINATE DEHYDROGENASE NITRATE REDUCTASE NITRITE REDUCTASE PHENYLALANINE MONOOXYGENASE PROLYL 3-HYDROXYLASE PROLYL 4-HYDROXYLASE PROTOCATECHUATE 3,4-DIOXYGENASE PROTOCATECHUATE 4,5-DIOXYGENASE RIESKE IRON-SULFUR PROTEIN RUBREDOXIN... 

PROLYL 3-HYDROXYLASE PROSTAGLANDIN H SYNTHASE PROTOCATECHUATE 3,4-DIOXYGENASE PROTOCATECHUATE 4,5-DIOXYGENASE... 

Pyrocatechase31 and protocatechuate 3,4-dioxygenase 86, both of which are typical examples of the intradiol cleavage, catalyze the reaction shown in Eqs. (2) and (12), respectively. 

Table 5. Amino acid compositions of native protocatechuate 3,4-dioxygenase and its subunits3...

Another protocatechuate 3,4-dioxygenase has been purified to homogeneity from p-hydroxybenzoate-induced cells of Acinetobactor calcoaceticuslil The enzymes from Acinetobactor and Pseudomonas are quite similar in their molecular weight, molecular size, and iron content. However, the specific activity of the Acinetobactor enzyme is about one-third of that of the Pseudomonas enzyme, despite of their similar iron contents117. ... 

The X-ray absorption spectra of a series of 28 model Fem complexes and those of ovatransferrin, protocatechuate 3,4-dioxygenase and catechol 1,2-dioxygenase have been analyzed, and appear to give information on the coordination number of the protein-bound iron. Thus the transferrin complexes appear to be six- or seven-coordinate, while the dioxygenase complexes could be five-or six-coordinate.816... 

The intradiol-cleaving enzymes represented by catechol 1,2-dioxygenase and protocatechuate 3,4-dioxygenase (PCD) catalyze the reactions shown in Figure 4. Both enzymes have iron(III) active sites and are spectroscopically well characterized. The enzymes exhibit a distinct bmgundy red color (Xmax 460 nm, 450 3500 cm ) that is... 

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). 

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