Benzene dioxygenases

Benzene dioxygenase is a complex enzyme consisting of three protein components, that catalyse the conversion of benzene to benzene cis-dihydrodiol. Give two reasons why this biotransformation should be carried out using whole cells as opposed to using enzyme preparations. 

The coordination of the Rieske cluster in the a subunit of benzene dioxygenase has been studied by site-directed mutagenesis. The replacement of His 98 or His 119 (corresponding to His 83/104 in NDO) by Cys resulted in a protein that was unable to coordinate a normal Rieske-type cluster (53). In the mutant His 98 Cys, a novel EPR spectrum with av = 1-94 was detected that is intermediate between... 

Extinction Coefficients and Ellipticities of the Rieske Protein from Bovine Heart bc Complex (ISF) and of the Rieske-Type Ferredoxin from Benzene Dioxygenase (FiIbed)... 

Fig. 12. EPR spectra of the Rieske fragment from the 6ci complex of Paracoccus denitrificans (ISFpd, top) and of the Rieske-type ferredoxin from benzene dioxygenase (FdBED, bottom). EPR conditions were as follows (ISF/FdBEn) microwave frequency, 9.021 GHz modulation amplitude, 1 mT/0.9 mT microwave power, 1 mW/9 mW temperature, 15 K/30 K.

ENDOR and ESEEM studies of phthalate dioxygenase (PDO) (7, 84), benzene dioxygenase (85), 2-halobenzoate 1,2-dioxygenase (86), 2,4,5-trichlorophenoxyacetate monooxygenase (86a), spinach bef complex (8), and the bci complexes from Rhodobacter capsulatus (7, 84) and in bovine mitochondrial membranes (87) (Fig. 16) have identified two nitrogen nuclei coupled to the [2Fe-2S] cluster with isotropic N... 

PDO, phthalate dioxygenase BDO, benzene dioxygenase 2,4,5-T-MO, 2,4,5-trichlorophenoxyacetate monooxygenase UHDBT, undecyUiydroxybenzothiazole. 

Thermodynamic Parameters of the Rieske Fragments from the be. Complexes of Bovine Heart (ISFb) (92) and Paracoccus dentrificans (ISFpd) (140) and of the Rieske-Type Ferredoxin FROM Benzene Dioxygenase (FdBED) (55)... 

A flavoprotein that transfers electrons to the ferredoxin, as in benzene dioxygenase (class II)... 

Crntcher SE, PJ Geary (1979) Properties of the iron-snlphnr proteins of the benzene dioxygenase system from Pseudomonas putida. Biochem J 111 393-400. 

Tan H-M, JR Mason (1990) Cloning and expression of the plasmid-encoded benzene dioxygenase from Pseudomonas putida ML2. FEMS Microbiol Lett 72 259-264. 

Figure 18.12. Benzene dioxygenase, toluene dioxygenase and naphthalene dioxygenase catalyzed dihydroxylation arenes to arene cis-dihydrodiols.

Class IIA Plant-type ferredoxin e.g. pyrazon dioxygenase Class MB Rieske Fe-S clusters in ferredoxin e.g. benzene dioxygenase and toluene dioxygenase... 

Boyd and Bugg 2006). The most widely researched and used is benzene cis-diol, or cw-DHCD, the reaction to produce it being catalyzed by benzene dioxygenase or TDO (Scheme 5). One of the applications of cis-DHCD is to synthesize the novel polymer PPR... 

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