Dioxygenase ring-opening

Fetzner, S., Enzymes Involve in the Aerobic Bacterial Degradation of N-Heteroaromatic Compounds Molybdenum Hydrolases and Ring Opening 2, 4-Dioxygenases. Naturwis-senschaften, 2000. 87 pp. 59-69. 

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... 

The following reaction is catalyzed by a dioxygenase from E. coli. Tire dioxygenase reaction opens the ring and the intermediate is cleaved hydrolytically. Propose a structure for the intermediate and a mechanism for the hydrolytic cleavage. See Fleming et al.382... 

K. Sugimoto, T. Senda, H. Aoshima, E. Masai, M. Fukuda, and Y. Mitsui. 1999. Crystal structure of an aromatic ring opening dioxygenase LigAB, a protocatechuate 4,5-dioxygenase, under aerobic conditions Structure FoldDes. 1 953-965. (PubMed)... 

In contrast to eukaryotes, bacteria such as Pseudomonas putida employ non-heme-containing dioxygenases in benzene metabolism [6-14. Harpel and Lipscomb [42] postulated that intradiol dioxygenases chelate the substrate (see 35) and the ring-opened product (see 36) releasing (Z,Z)-muconic acid (4a) (see Scheme... 

Pseudomonas putida also ring opens catechol via an extradiol dioxygenase, possibly through 38 [42], to yield 2-hydroxy-6-oxo-2,4-hexadienoic acid (Scheme... 

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