Dioxygenases extradiol

Dihydroxyphenylacetate extradiol dioxygenase from Klebsiella pneumoniae strain M5al contains magnesium and is not activated by Fe (Gibello et al. 1994). 

Boldt YR, Ml Sadowsky, LBM Ellis, L Que, LP Wackett (1995) A manganese-dependent dioxygenase from Arthrobacter globiformis CM-2 belongs to the major extradiol dioxygenase family. J Bacterial 177 1225-1232. 

Spence EL, M Kawamukai, J Sanvoisin, H Braven, TDH Bugg (1996) Catechol dioxygenases from Escherichi coli (MhpB) and Alcaligenes eutrophus (MPCI) sequence analysis and biochemical properties of a third family of extradiol dioxygenases. J Bacteriol 178 5249-5256. 

C subfamily of type 1 extradiol dioxygenases (Mars et al. 1999). The alternative extradiol fission of 3-chlorocatechol may take place between the 1 and 6 positions (distal fission), and this has been shown for the 2,3-dihydroxybiphenyl 1,2-dioxygenase from the naphthalene sulfonate degrading Sphingomonas sp. strain BN6 (Riegert et al. 1998). 

Riegert U, G Heiss, P Fischer, A Stolz (1998) Distal cleavage of 3-chlorocatechol by an extradiol dioxygenase to 3-chloro-2-hydroxymuconic semialdehyde. J Bacterial 180 2849-2853. 

Asturias JA, LD Eltis, M Prucha, KN Timmis (1994) Analysis of three 2,3-dihydroxybiphenyl 1,2-dioxygenases found in Rhodococcus globerulus P6. Identification of a new family of extradiol dioxygenases. J Biol Chem 269 7807-7815. 

Happe B, ED Eltis, H Poth, R Hedderich, KN Tunmis (1993) Characterization of 2,2, 3-trihydroxybiphenyl dioxygenase, an extradiol dioxygenase from the dibenzofuran- and dibenzo-/ -dioxin-degrading bacterium Sphingomonas sp. strain KWl. J Bacteriol 175 7313-7320. 

Schmid AS, B Rothe, J Altenbuchnerm W Ludwig, K-H Engesser (1997) Characterization of three distinct extradiol dioxygenases involved in mineralization of dibenzofuran by Terrabacter sp. strain DPO 360. J Bacterial 179 53-62. 

Dioxygenases that open the aromatic ring in the vicinal position to the o-diols are called extradiol dioxygenases. A mononuclear Fe(II) or Mn(II) complex forms their active site. This is, for instance, the case of 2,3-dihydroxybiphenyl-1,2-dioxygenase of Pseudomonas sp. Strain KKS102, the square pyramidal geometry of which is schematized in Figure 3.3... 

Fig. 8. Model for oxygen activation by extradiol dioxygenases. PCA, protochatechuic add.

The extradiol dioxygenases are more common than the intradiol enzymes, and are more diverse in their reactions.1379 Examples are catechol 2,3-dioxygenase (from Pseudomonas arvilla and Ps. putida) and protocatechuate 4,5-dioxygenase from Ps. testosterone These are colourless and... 

EXAFS studies and the aforementioned high-resolution crystallography indicate that the catechol snbstrate binds in an asymmetric fashion to the iron(II) center with Fe-Ocatechoiate bond lengths that differ by 0.2 0.4 A. These structural parameters are in excellent agreement with those reported for synthetic iron(II)-monoanionic catecholate complexes, and, on the basis of this comparison, it was proposed that the catechol binds to the iron(n) center as a monoanion. This notion was supported by subsequent UV-resonance Raman andUV-vis studies. " The monoanionic nature of the catechol substrate in extradiol dioxygenases is in sharp contrast with the dianionic catecholate character commonly found in iron(III) complexes. This difference can be rationahzed by the differing Lewis acidities of the metal centers in their divalent and trivalent oxidation states. 

There are relatively few characterized metaUoproteins having mononuclear Mn sites. By far the best characterized mononuclear Mn site is shown in Superoxide Dismutase, although there are several other proteins that appear to have tightly bound mononuclear sites, including an extradiol dioxygenase, and several members of the cupin family. 

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